Scientific Intelligence — Zoology. 181 



fore described, which he had noticed, is somewhat concealed under 

 the skin of the caterpillar. The animal at a certain period swells 

 at the thoraci region, and becomes extremely sensitive to the touch 

 in this part, the skin being, in fact, in a state of inflammation. On 

 cutting open the skin at this place, Professor Agassiz found beneath 

 it a four-winged insect, before it had passed into the chrysalis state. 

 The wings were long enough to extend half the length of the perfect 

 insect. The posterior pair he found to be membraneous bags, some- 

 what flattened, like the respiratory vesicles of marine worms, with 

 distinct ribs, which are blood-vessels. The anterior pair are also 

 bags, with their upper half stiff and inflexible, like the elytra of 

 coleoptera. The legs are tubular, but not joined, as in the perfect 

 insect. The jaws are changed into two long tubes, which are bent 

 backwards, as are also the antennae. In the chrysalis, the wings 

 are flattened and soldered together, as are the legs and sucking-tubes, 

 which are bent backwards. The order of development of the differ- 

 ent parts and the coleopterous condition at an incomplete stage, 

 show that naturalists have been in error in placing chewing insects, 

 as the coleoptera, above the sucking insects. The order should be 

 reversed. Professor Agassiz said that he had confirmed his obser- 

 vations in many specimens, by examining them just at the moment 

 when the skin begins to split on the back. — American Annual of 

 Scientific Discover^/, p. 327. 



16. On the Zoological Character of Young Mammalia. — At the 

 meetins^ of the American Association for the Promotion of Science, 

 Professor Agassiz remarked, that zoologists have, in their investiga- 

 tions, constantly neglected one side of their subject, which, when 

 properly considered, will throw a great amount of new light on their 

 investigations. Studying animals, in general, it has been the habit 

 to investigate them in their full grown condition, and scarcely ever 

 to look back for their characters in earlier periods of life. We scarcely 

 over find, in a book of natural history, a hint as to the difference 

 which exists in the young and old. Perhaps in birds, the colour of 

 the young may be noticed ; and it is generally known, that the young 

 resemble the female more than the male ; but as to precise investi- 

 gation of the subject, we are deficient. But if the early stages of life 

 have been neglected, there is one period in the history of animals 

 which has been thoroughly investigated, for the last twenty-five years, 

 — embryology. The changes which take place within the egg itself, 

 and which give rise to the new individual, have been thoroughly ex- 

 amined; but, after the formation of the new being, the changes in 

 its form which it passes through, up to its full grown condition, have 

 been neglected. It had been his object to investigate this subject, 

 because he had been struck with the deficiency there is on this point 

 in our works ; and in making this investigation, he had found that 

 the young animals, in almost all classes, differ widely from what they 

 are in their full-grown condition. For instance, a young bat, a young 



