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SUMMARY OF CURRENT RESEARCHES RELATING TO 
Biology of Chermes.* * * § — Dr. K. Eckstein continues to write on this 
interesting subject ; the details of the synonymy of the various species 
are now somewhat matter for specialists. We have on several occasions 
already indicated the methods of observation 
Embryonic Development of Chalicodoma muraria.| — Herr J. 
Carriere gives a brief account of the results of his investigations into 
the embryonic development of this Insect. The mesodermal plate, which 
is bounded by two grooves which converge anteriorly, consists of several 
layers before the period of invagination, and is not rolled into a tube as 
the result of this process. Shortly after the growth of the plate at its 
anterior end the anterior ectodermal rudiment appears in front of it and 
the folds in the blastoderm ; later on no corresponding rudiment is seen. 
In both regions there is cell-growth, and, as a result, the uppermost 
blastoderm -layer becomes the ectoderm, and the rudiment of the endo- 
derm is set free. From the beginning to the end of development the 
cells that form the endoderm and its derivatives differ both in size and 
appearance from those of the mesoderm and its derivatives. 
The labrum consists of two independent folds which rise up on either 
side of the median line ; they come together slowly. Each segment of 
the three pairs of gnathites and of the thorax, as well as the first eight 
segments of the abdomen, have a rudiment of a stigma, but only those 
of tlie meso- and metathorax and of the abdomen pass into the permanent 
stigmata. That of the anterior gnathite- bearing segment gives rise to 
the anterior tentorial rudiment, those of the median to the chitinous 
bar of the flexor mandibuli, and those of the hinder to the rudiment of 
the posterior tentorium. The salivary glands are derived from the 
rudiments of the stigma of the prothoracic segment. The first structure 
formed from the permanent stigmata is not the long tracheal trunk, but 
a short tube which ends blindly at the anterior boundary of the segment. 
This body calls to mind, in a very striking way, the structure of nephridia, 
and, indeed, the stigmata are the only organs of the Insect-body which 
can be compared to the efferent ducts of segmental excretory organs. 
The Malpighian vessels appear in the eleventh segment, but it is un- 
certain whether they are homologous with the rudiments of stigmata. 
The rudiments of the thoracic feet appear with those of the stigmata, 
and disappear when the embryo assumes the larval form ; those of the 
abdominal somites do not appear till after them, and persist for a short 
time only. 
Myrmecophilous Oak-galls. § — On the authority of Dr. H. C. M‘Cook 
(‘The Honey-ants of the Garden of the Gods,’ Philadelphia, 1882), 
Prof. F. Delpino describes a species of ant, Myrmecocistus melliger, which 
has a caste of workers metamorphosed into honey-bags. The abdomen 
is distended into the size and form of a grape, and is full of honey, on 
which the other members of the colony feed when hungry. This ant 
appears to range through Mexico, New Mexico, Colorado del Sul, and 
possibly into California. It is of nocturnal habits, and obtains the 
* Zool. Anzeig., xiii. (1890) pp. 86-90. 
t See this Journal, 1889, pp. 380, 506, 745. 
X Zool. Anzeig., xiii, (1890) pp. 69-71. 
§ Malpighia, iii. (1889) pp. 349-52 (1 pi.). 
