ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
461 
he has succeeded in producing varieties* * * § identical in appearance with 
those occasionally found in nature. He also criticizes Mr. Cockerell's 
theory that yellow is anterior to white in the course of evolution, and 
argues that the course of evolution has really been white, yellow, red. 
Early Stages of Development in Eggs of Insects, f — Dr. H. 
Henking, in his second memoir, deals with spermatogenesis in Pyrrho- 
coris apterus, and its relation to egg-development. He finds that the 
primordial sperm-cells correspond to the primordial ova ; both forms of 
cells contain the characteristic number of twenty-four chromosomes. The 
spermatocytes of the first order correspond to unripe ova ; both increase 
considerably in size, and both develope a j>roportionately large vesicular 
nucleus, in which yolk-spherules are produced. The formation of the 
first polar globules corresponds to the first division of the spermatocytes. 
In both cases there is a “ reduction-division,” for twelve chromosomes are 
found in each new cell. The formation of the second polar globule 
corresponds to the second division of the spermatocytes. The twelve 
chromatic elements are directly halved by “ equation-division.” 
The following points are noticeable in the spermatosome : — The secon- 
dary nucleus is formed from the peripheral connecting fibres and by divi- 
sion of the spindle-fibres ; the central bundles of the former give rise to 
the mitosoma ; the paired secondary nucleus attaches itself to the nucleus 
which will become the head of the spermatozoon. The portion of the 
mitosoma which becomes attached to the nucleus becomes chromatic 
and wanders to the anterior end of the spermatozoon. It is probable 
that small quantities of chromatin substance pass into the secondary 
nucleus and the mitosoma. There are two distinct kinds of normal 
spermatozoa. Some contain only eleven chromatic elements, while 
others have in addition a chromatic element which remains undivided 
and is probably to be regarded as a nucleolus. 
Insects injurious to Forest and Shade Trees.J — Prof. A. S. Packard 
publishes, in the reports of the United States Entomological Commission, 
a report on Insects injurious to Forest and Shade Trees ; it is a subject 
to which, as yet, but little attention has been given. The materials are 
dealt with in twenty chapters, under the heads of various trees, such as 
oak, elm, hickory, and so on. There is a brief explanatory introduction. 
Insect-larva eating Rust on Wheat and Flax. § — Messrs. N. A. 
Cobb and A. Sidney Olliff have observed orange-coloured larvae (of 
a species of Cecidomyia) on many specimens of rusted wheat. Observa- 
tion showed that the larvae fed greedily on the rust. They suggest 
further study of the relations between insects and mites and fungi, and 
propose next season to continue their investigations. The larvae are 
described. 
Role of Nucleus in Formation of Muscular Reticulum in Larva of 
Phrygane.|| — M. E. Bataillon believes he has shown that the transverse 
* In a note to the ‘ Entomologist,’ March 1891, the author warned collectors 
against buying varieties, since such might now be easily manufactured by the 
methods described as having been employed in his experiments. 
f Zeitschr. f. Wiss. Zool., li. (1891) pp. 685-736 (3 pis.). 
% U.S. Department of Agriculture, Washington, 1890, vi. and 955 pp., 38 pis., 
and 306 woodcuts. § Ann. and Blag. Nat. Hist., vii. (1891) pp. 489-93 (3 figs.). 
§ Comptes Rendus, cxii. (1891) pp. 1376-8. 
