Sexual Dimorphism In The Animal Kingdom; A Theory Of The Evolution Of Secondary Sexual Characters

Paperback | January 12, 2012

byJoseph Thomas Cunningham

not yet rated|write a review
This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1900. Not illustrated. Excerpt: ... after the generative products have been once discharged. The increased size of the eyes in the mature male may be due to the greater use made of the organs, the ripe male perhaps ceasing to conceal himself and swimming about actively in search of the female. A similar difference in size occurs in the Eel. The largest male eel described did not exceed 19 inches in length, while females, when adult, are from 27 to 39 inches long. Eels only become sexually mature in the sea, and like the conger die after breeding once. According to Grassi and Calandruccio, the discoverers of the Leptocephalus larva of the eel, the eyes are larger in mature eels, both male and female, than in the immature specimens which inhabit fresh water. Sub-ordek Anacanthini.--Pleuroncctidcc.--In this family the males are invariably smaller than the females. This fact can be demonstrated in two ways: (a) by ascertaining the average size of a large number of males and a large number of females caught on grounds frequented by the adults of both sexes; (b) by ascertaining the size of the smallest mature and largest immature specimens of both sexes, and the proportion of mature and immature specimens at intermediate sizes. Thus in the northern part of the North Sea the smallest mature female plaice were 13 in. long, the smallest mature males, 9 in. The largest immature females were 18 in. long, the largest immature males 16 in. According to Dr. Fulton the ratio of the average length of female plaice to that of males was 114 to 100, of turbot 118 to 100. This difference of size is the opposite to that which occurs frequently in mammals and birds, and cannot be attributed to a general inferiority of size in the male sex. On the other hand, it is difficult to discover a reason for the larger size of f...

Pricing and Purchase Info

$27.95

Out of stock online

From the Publisher

This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1900. Not illustrated. Excerpt: ... after the generative products have been once discharged. The increased size of the eyes in the mature male may be due to the greater ...

Format:PaperbackDimensions:96 pages, 9.69 × 7.44 × 0.2 inPublished:January 12, 2012Publisher:General Books LLCLanguage:English

The following ISBNs are associated with this title:

ISBN - 10:0217053068

ISBN - 13:9780217053068

Look for similar items by category:

Customer Reviews of Sexual Dimorphism In The Animal Kingdom; A Theory Of The Evolution Of Secondary Sexual Characters

Reviews