ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 73 



tion as the same axis of the mother. The author concludes with the 

 generalization that, in insects, the egg-cell has the same orientation as the 

 mother, has a cephalic and a caudal pole, a right and left side, and a dorsal 

 and a ventral surface, and that these correspond to those of the embryo. 



Artificial Parthenogenesis.* — Herr A. Tichomiroff has investigated 

 the parthenogenesis of the ova of Bomhyx mori. The really parthenogenetic 

 reproduction is confirmed, and it is also shown that ova which would not 

 of themselves develop parthenogenetically might be induced to do so by 

 certain stimuli. These stimuli consisted in rubbing the unfertilized ova 

 with a brush, or in dipping them for two minutes in concentrated sulphuric 

 acid, and then washing them. In both cases a percentage of the stimulated 

 ova developed, but in the unstimulated parthenogenetic lot none seemed 

 able to do so. 



Thoracic Salivary Glands homologous with Nephridia.f — As the 

 result of some studies on the structure of lower insects (Campodea, Lepisma, 

 Madilis, &c.), Herr IST. Nassonow has been led to the conclusion that a 

 portion of the efferent ducts of the male genital organs develope from the 

 mesoderm, and that the thoracic salivary glands of insects are homologous 

 with the segmental organs of worms. It is further probable that the 

 oviducts also, several accessory glands in association with the reproductive 

 organs, and likewise the abdominal tubules of Campodea and Madilis are 

 remains of segmental organs. 



Leydig's Cord.| — In studying the eggs of Blatta germanica and some 

 embryos of Melloe proscaraheus, Herr J. Nussbaum noted the presence of 

 an organ which he regards as homologous with the notocord of vertebrates. 

 It is, however, of mesodermic origin. The cord found by Leydig in 1862 

 is regarded as homologous to the external neurilemma of the nervous 

 system plus the cellular-connective tissue of the abdominal diaphragm. 



Ants and Ultra- Violet Rays.§— Whilst Sir J. Lubbock considers that 

 ants perceive the ultra-violet rays by means of their eyes, Graber finds, by 

 removing these organs from tritons, &c., that it is by the skin that these 

 rays are perceived. Prof. A. Forel has made experiments in order to 

 answer the question whether ants perceive these rays by means of their 

 eyes, or by the skin ; and he finds that it is mainly by the former organs, but 

 admits that " photodermatic " perception may accompany the optic sense. 

 Camponotus ligniperdus and Formica fusca served for his experiments, and a 

 " solution d'esculine " was used for absorbing the ultra-violet rays. 



Insect-skin. |] — ^Prof. C. S. Minot distinguishes on the cuticle of insect 

 larvae a very thin lamella, often markedly pigmented. The surface is 

 usually divided into areas, each of which corresponds to a subjacent epi- 

 dermal cell. The middle of each area usually projects, and the lamella 

 covers the elevations with its pigmented sheath. The form and pigmenta- 

 tion of these areas vary greatly, and may be utilized for diagnostic purposes. 

 In primitive forms like Peripatus and in some Orthoptera, the elevation of 

 the thick cuticle over each cell bears a number of small points. The 

 boundaries of the areas may disappear, and the points remain or be reduced 

 in number. Or the elevations may remain and the points fuse together. 



* Arch. f. Anat. u. Physiol. (Physiol. Abtheil.) 1886, Supplement, pp. 35-6. 



t Biol. Centralbl., vi. (1886) pp. 458-62. 



t Kosmos (Polish) 1886. Of. Arch. Slav, de Biol., ii. (1886) p. 291. 



§ Arch. Sci. Phys. et Nat., xvi. (1886) pp. 346-50. 



II Arch. f. Mikr. Anat., xxviii. (1886) pp. 37-48 (I pL). 



