ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
187 
formation of crystalline cones is not an external excretion, as Claparede 
thought, but an internal excretion ; within each of Semper’s cells there 
appears a small mass of substance of the crystalline cone. The rhabdom 
is not an excretion of the cells of the retinula, but a modification of the 
protoplasm of these cells. The facets of the cornea are not formed by a 
layer of cells different from those which form the crystalline cones. 
The leucocytes convey the pigment of the eyes of the larva to the 
epidermic cells which become converted into ommatidia, and they trans- 
form the pigment of the eyes of the larva into the pigment of the eyes of 
the imago. 
The optic ganglion of the latter is derived from that of the former ; 
the only new formation is the layer of nerve-bundles. 
Spermatogenesis of Bombyx Mori.* — Mr. K. Toyama Nogakushi 
was struck with the varieties of cellular elements which are to be found 
in the testes of a larva after the fourth moult. Near the blind end of 
each testicular follicle there is a large cell, around which small cells are 
arranged concentrically. If the early history of this cell be traced it 
will be found that it is not a germ-cell, as Verson states, but corresponds 
rather to the supporting cells of the testes of Vertebrate^, or the rachis 
of the Ascaris egg-string. Though not constantly present in the gonads 
of Lepidoptera this cell is not rare. 
As the more developed sperm elements always lie near the vas 
deferens, while the younger elements lie near the blind end of the 
follicle, it is possible to distinguish the formative, the growing , the 
ripening zones, and the zone of metamorphosis. Brief notes are given 
on each of these, and a more detailed and illustrated account is 
promised. 
Life-history of Bombycine Moths.j — Prof. A. S. Packard, in view 
of the philosophical importance of the study of caterpillars, recommends 
that i 
(1) The larvae should be treated as though they were adult, indepen- 
dent animals, and their specific and generic as well as family characters 
should be worked out. 
(2) The origin of mimetic and protective characters should be traced, 
and the time of larval life when they are assumed ascertained. 
(3) This will involve the history of the development of the more 
specialized setae, spines, tubercles, spots and other markings. 
(4) Facts should be obtained regarding the ontogeny of American 
species and genera ; as these, when added to what is known of the life- 
histories of Bombyces from other continents, may lead to at least a 
partial comprehension of the phylogeny of the higher Lepidoptera. 
The author proceeds to give notes on the early stages of Dryopteris 
rosea , the larva of La cosoma chiridota , and of that of Perophora 
melsheimerii ; as to this last he notes the adaptational characters, among 
which we may note its wonderful power of shortening its body and thus 
dilating it so as to enable it to retain its hold in its case and prevent its 
being drawn out by birds, as well as its stout jaws which enable it to 
* Zool. Anzeig., xvii. (1894) pp. 20-4. 
f Annals New York Acad. JSci., viii. (1893) pp. 41-92. 
