ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 231 



Respiratory Organ of Scutigeridge.* — Dr. E. TSmosvary describes 

 the respiratory organ of the Scutigeridse as being much flattened, about 

 1 mm. long and 1*5 mm. broad, with the form of two kidneys fused along 

 their inner edge ; the stigmatic orifice leads into a respiratory cavity, the 

 upper and lower surface of which are formed by basal membrane, the 

 respiratory tubes arising only from the anterior and lateral margins ; these 

 tracheae are very fine and hyaline, and gradually but regularly narrow to 

 their blind end ; they never anastomose with one another along their course, 

 they are quite homogeneous, and show no indication of spiral filaments. 

 There is no peritoneal investment, such as is found in other Tracheata ; or, 

 if it is present, it is modified. The glandular appearance of the tubes, 

 which has led some authors to ascribe a glandular function to these organs, 

 is explained as being due to the presence of wandered cell-nuclei of the 

 tracheal matrix, which are found between the tubes. 



5. Araclinida. 



Non-nucleated Blastoderm-cells.f — Korottneff, Grassi, and others have 

 described amoeboid cells becoming blastoderm-cells, but at certain stages 

 without nuclei. Herr W. Schimkiewitsch has noted the same phenomenon 

 in the development of spider ova. Since he had traced the non-nucleated 

 cells, however, from the division of the germinal vesicle and surrounding 

 protoplasm, he, of course doubted the possibility of the nucleus being 

 absent. He treated the sections, preserved in Kleinenberg's fluid, with a 

 weak solution of ammonia, and stained them with borax-carmine, with the 

 result that in the densely stained elements, rounded unstained corpuscles 

 could be detected, like empty nuclei. This he compares with results of 

 other observers, and suggests that the unstained bodies are true nuclei, 

 from which the chromatic substance has been passed into the surrounding 

 protoplasm. He regards it, then, as probable that all the so-called non- 

 nucleated blastoderm-cells are simply instances of the temporary disappear- 

 ance of the chromatin nuclear substance. 



Embryology of Spiders. | — Herr J. Morin communicates a brief notice 

 of his researches on the embryology of spiders. His investigations were 

 based upon Theridion, Pholcus, Drassus, and Lycosa, but refer especially 

 to the first of these. 



(a) After being laid, the ovum of Theridion exhibits two egg-envelopes, 

 the chorion and the vitelline membrane. In the centre lies the germinal 

 vesicle, surrounded by finely granular protoplasm giving off strands into 

 the surrounding yolk. In two hours the nucleus divides into two, four, 

 and eight segments, but the yolk remains still undivided. When the eight- 

 cell stage is reached, however, the yolk also divides into eight pyramids, 

 with a central segmentation-cavity. The segments multiply regularly and 

 each contains a single nucleus. The nuclei move towards the surface, and 

 when the number of segments is 128, the outer nucleated portions are 

 separated from the internal yolk portions, which then flow together again. 



(h) Soon afterwards the embryo is seen to consist of three kinds of 

 cell, (1) the layer surrounding the whole (ectoderm), (2) a number of cells 

 separated from the former and lying immediately beneath it on the ventral 

 surface (mesoderm), and (3) several cells of similar origin which have 

 penetrated into the yolk (endoderm). In Theridion there is no " primitive 

 cumulus " such as is formed in Pholcua, Drassus, &c. This cumulus is an 



* Mathemat. u. Naturwiss. Bericlite aus Ungarn, i. (1883) pp. 175-80 (1 pi.). 

 t Arch. Slav, de Biol., ii. (1886) pp. 26-7. 

 X Biol. Cenfi-rtlb]., vi. (1887) pp. 658-63. 



