506 SUMMARY OF CURRENT RESEARCHES RELATING TO 



inclined to accept Hatschek's statement that the brain arises from the 

 lateral parts of ectoderm laid down separately. 



A Spinning Dipteron.* — Prof. J. Mik describes a remarkable veil 

 which the male of Hilara sartor Beck, carries about with him in his flight. 

 This veil is a thick filamentous tissue, without any " sort of seam in its 

 longitudinal axis," or " S-shaped threads," as Becken describes. It is not 

 borne on the back of the abdomen of the male, but is held on the under 

 surface of the body by the feet. 



Biology of Gall-producing Species of Chermes.t — Dr. F. Low has 



a contribution to the interesting subject of the biology of gall-producing 

 species of Chermes which is now attracting so much attention. His 

 experiments enable him to confirm two of the statements of Blochmann 

 and Dreyfus — the wandering of the winged individuals of the first or 

 gall-generation of Chermes ahietis from the pine to another species of 

 Conifer, and the division of this generation into two unequal parts, each 

 of which forms the commencement of a special series of developmental 

 changes. He also makes a contribution to the literary side of the 

 question. 



Dr. L. Dreyfus | has again § a communication on the subject ; he finds 

 that Ch. Tiamadryas must cease to be regarded as an independent species, 

 and the animals which have been so called must be considered to belong 

 to the developmental series of Ch. strohilohius ; there are, therefore, no 

 species which can now be said to be confined to the larch. 



Egg of Melolontha viilgaris.|l — Dr. A. Voeltzkow has made a study 

 of the development of the egg of Melolontha vulgaris, but unfortu- 

 nately he was not able to investigate the earliest stages. The germinal 

 layers are formed in the manner first described by Kowalevsky for Insects, 

 namely, by invagination in the middle line of the germ-stripe, the 

 groove thus formed being converted into a tube ; this tube is flattened 

 out in a dorso-ventral direction, becomes cut off from the blastoderm, 

 and differentiated into an outer and an inner layer. The cells of either 

 layer fuse completely with one another, so that no sign is left of the 

 previous tube or cleft. The author is not in agreement with Heider, for 

 he is unable to accept the account of the differentiation of the lower 

 layer into two distinct cell-layers. A very important point in Heider's 

 memoir is the account of the formation of the mid-gut; but Dr. 

 Voeltzkow's own investigations, coupled with a critical notice of the work 

 of other observers, seem only to lead him to the conclusion that the 

 question of its origin is well worthy of renewed investigation, which he 

 proposes to take with Blatta as his subject. 



Anatomy of Blattidse.lF — Dr. E. Hasse states that Mr. B. A. 

 Minchin's lately discovered ** organs in Periplaneta orientalis are, as 

 their discoverer supposed, stink-glands ; it may be easily proved in the 

 larvfe. The hairs which take up the secretion of the glands and diffuse 

 it call to mind those described by Fritz Miiller as associated with the 

 stink-clubs of the females of Maracuja. In both the secretion appears 

 to be of an oily character. Comparable also are the eversible dermal 



* Verh. K. K. Zool.-Bot. Gesell., xxxviii. (1888) pp. 97-8. 



t Zool. Anzeig., xii. (1889) pp. 290-3. 



I T. c, pp. 293-4. § See this Journal, ante, p. 380. 



II Arbeit. Zool.-Zoot. Inst. Wurzbiarg, iv. (1889) pp. 49-64 (1 pi.). 



Tl Zool. Anzeig., xii. (1889) pp. 169-72. ** See ante, p. 204. 



