ZOOLOGY. 305 



prove extraordinarily dark. But there is a singularity in the 

 fact that the darkest specimens so bred rarely open their wings." In 

 opposition to the objections that such variations were the result of 

 disease, it was shown that many of the specimens so varied were of 

 larger and finer growth than the ordinary specimens. In the course 

 of the remarks on this subject, Mr. J. Lubbock suggested the impor- 

 tance of ascertaining the effect of feeding successive generations of 

 the same insect with substances calculated to produce variations, and 

 expressed a hope that some entomologists would extend the observa- 

 tions over a series of years. 



DISTRIBUTION OF THE NERVES. 



In a paper recently communicated to the Royal Society, Mr. Beale 

 states that he has ascertained that the nerves distributed to the volun- 

 tary muscles of the frog do not terminate in free ends, but there is 

 reason for believing that complete nervous circuits exist. In all cases 

 the fibres resulting from the division of the ordinary nerve-fibres are 

 so fine that many cannot be seen with a less magnifying power than 

 1,000 diameters. And there is evidence of the existence of fibres 

 which could be only demonstrated by employing a much higher magni- 

 fying power. It is by these very fine fibres alone and their nuclei that 

 the tissues are influenced. The ordinary nerve-fibres are only the 

 cords which connect this extensive peripheral system. Mr. Beale also 

 finds the same arrangement in the nerves of man and the higher mam- 

 malia. 



RED CORPUSCLES IN THE BLOOD OF VERTEBRATA. 



In a recent communication to the Zoological Society, London, Prof. 

 Gulliver, F. R. S., stated that there have been two parties differing 

 essentially in their conclusions as to the structure of the corpuscles 

 of the blood, both correct as far as they went. The first party, of 

 which Hewson was the representative, insisted that the red corpuscle 

 is a vesicle inclosing a nucleus ; the second party, of which Dr. Hodg- 

 kin and Mr. Lister were the chiefs, were equally certain that Hewson 

 was wrong, and that the red cprpuscle has no nucleus. Prof. Gulliver 

 showed, as the result of his researches from 1839 to '42, that the red 

 corpuscle of mammalia is destitute of any nucleus, while the red 

 corpuscle of oviparous vertebrata, on the other hand, always has a 

 nucleus. Hewson, having drawn his description from the corpuscles 

 of fish or fowls, was quite right so far ; and Hodgkin and Lister, having 

 examined only the corpuscles of man, were equally correct in the same 

 restricted sense. Thus Mr. Gulliver's observations not only com- 

 pletely cleared up the long existing discrepancies between former 

 observers, but fairly settled this " vexed question of nucleus," as it 

 had so long been called. 



Further, he asserted that the result of his observations clearly was, 

 that the most important, because the most universal and fundamental, 

 difference between the two great divisions of the vertebrate sub- 

 kingdom, is the presence or absence of this nucleus ; so that any one 

 possessing a good microscope could at once plainly see the difference 

 between the red corpuscles of these two divisions of vertebrata. It 

 was also shown that this character is perfectly good from before birth, 

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