ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
713 
represents tlie degenerated nucleus. The spongy cortex is a most notable 
illustration of that vacuolated structure of protoplasm which Biitschli 
has described in Protozoa. In the period of activity the products 
accumulate in the vacuoles, they assume firmer consistence, they are 
incorporated into the original plasma, and the whole structure swells. 
As to the function of these curious glands, it must be noted that they 
never communicate with the free surface of the silkworm, but that their 
products have to expand between the hypodermis and the cuticular husk. 
Prof. Verson shows that these glands, besides facilitating the detachment 
of the older cuticular husk, function actively and as it were vicariously 
when the Malpighian tubules are temporarily out of function, and form 
material which yields on evaporation crystals of oxalate of lime and uric 
acid — in other words, an excretion like that of the renal tubules. 
Evolution of the Hymenoptera.* * * § — Prof. F. Delpino suggests the 
following scheme of development of the families of Hymenoptera, partly 
derived from that of the plants on which they feed : — (1) Tenthredinideae , 
or phyllophagous Hymenoptera ; (2) Siricidse, or xylophagous Hymeno- 
ptera (contemporaneous with the evolution of the Coniferae) ; (3) Ich- 
neumonidse , or pupivorous Hymenoptera; (4) Fossori ; (5) Vesparii ; 
(6) Apiarii ; (7) Formicarii. In this series the biological advances pari 
passu with the morphological evolution. The Siricidas are all more or 
less gluttonous of honey. The evolution of a long oviduct advances 
from the Siricidae to the Ichneumonidae ; the conversion of this oviduct 
into a poisonous sting takes place between (4) and (7). The property 
of pupivorous larvae connects (3) and (4). The nidifying character 
connects (4), (5), (6), and (7). The property of socialism connects 
(5) , (6), and (7). The character of producing different castes connects 
(6) and (7). According to this scheme the family of ants represent 
the most recent evolution of the Hymenoptera. 
Monograph of Sand-Wasps.t — Herr A. Handlirsch publishes the 
fifth part of his monograph on sand-wasps, including a systematic study 
of the American genus Monedula , in which he distinguishes 44 species, 
half of them new. 
Development of Hydrophilus piceus.J — Dr. K. Heider makes a 
reply to the criticisms of Prof. Graber, § in which he urges that much of 
his work was done before his critic published the results of his studies ; 
some of the points referred to are merely petty, and were not judged to 
be worth special notice. 
Development of Platygaster instricator.|j — Mr. N. Kulagin has 
made a study of the eggs laid by this parasitic insect in the larvas of 
Cecidomyidae. The species examined was found to lay from two to five 
eggs in a cocoon, and these eggs are either not simultaneously developed 
or some only undergo development. The blastoderm is formed of 
elements of the division which extends in regular order from the centre 
to the periphery of the egg ; the other elements of division remain in 
* Malpighia, iv. (1890) p. 7. 
f SB. K. Akad. Wiss. Wien, xeix. (1890) pp. 77-166 (1 pi.). 
X Zool. Anzeig., xiii. (1890) pp. 428-30. 
§ See this Journal, ante , p. 451. || Zool. Anzeig., xiii. (1890) pp. 418-24. 
