172 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
(2) Faint indications of a similar nature are obtained by the use of 
sodium cyanide. 
(3) No such reactions can be obtained with ferrocyanides, sulpho- 
cyanides, ammonium salts, nitrates, nor with other salts of potassium 
and sodium, nor with any of many other reagents examined. 
(4) When exposed under similar conditions to the action of lithic 
sulphate, a fine purple-pink colour is produced, staining the salt. 
Similar, but more or less faint, results are obtained with several other 
reagents, including baric chloride, sodic arsenate, and succinic and 
salicylic acids. A reaction with zincic sulphate seems to be somewhat 
intermediate between (1) and (4). 
(5) All of these reactions are confined to the Pieridae, and are ob- 
tainable from no other yellow or chestnut Ehopalocera or Heterocera yet 
examined. 
Oogenesis, Maturation, and Fertilization.* — Herr H. Henking 
makes further contributions of much importance to our knowledge of 
the early processes in the development of insect ova. His studies refer 
to PyrrJiocoris apterus L. and Hydrometra Najus Deg. among Hemiptera, 
Agelastica alni L. and Donacia (sericea L. ?), Lampyris ( Lamprorrhiza ) 
splendidula L ., Tenebrio molitor , Adimonia tanaceti L., Crioceris asparagi 
L., Lina aeneaL ., Gastroides polygoni L. among Coleoptera, Lasius niger 
L., Bhodites rosse L. among Hymenoptera, Bombyx mori L., Leucoma 
salicis L. among Lepidoptera, Musca vomitaria L. among Diptera. In 
regard to many of these types a wealth of detailed description is given, 
referring not only to oogenesis, polar body formation, fertilization, but, 
in some cases, to spermatogenesis, polyspermy, parthenogenesis, &c. 
We shall, however, restrict ourselves here to the general results. 
The ova have three envelopes, (a) the vitelline membrane (oolemm), 
(b) the shell or chorion, perforated by micropyle or micropyles, and 
(c) a glandular secretion. Within the vitelline membrane is the super- 
ficial germinal blastem which is continued into a network through the 
yolk. 
The germinal vesicle of the mature ovum disappears, leaving the 
chromosomata in a double row in the equatorial plate of the first directive 
spindle ; in the subsequent formation of the first polar body there is a 
reduction in the number of chromosomata. While the two daughter- 
nucleus-plates go apart, the outer with the chromosomata of the first 
polar body, the inner with those of the Spaltkern or second directive 
spindle, there appears between them a (first) achromatic polar body, a 
“ Thelyid,” formed from the greater part of the substance of the connect- 
ing threads and of the cell-plate. This first Thelyid, which is some- 
times like the young Nebenkern of a spermatide, is associated with the 
first polar body. 
Without a resting stage the chromosomata of the Spaltkern divide, 
forming the second polar nucleus, whose formation may be associated 
with an “ achromatic pseudospindle,” often with distinct cell-plate, — the 
second Thelyid ( Agelastica , Lampyris , Pyrrhocoris ) ; or the halving of the 
chromosomata may occur without a separation of achromatic substance 
( Pieris , Musca, Lasius, Bhodites , Tenebrio). 
* Zeitschr. f. Wiss. Zool., liv. (1892) pp. 1-274 (12 pis., 12 figs.). 
