ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 447 



general or special sensations. As the most important element in 

 these organs is a single cell, the authors purposely avoid applying to 

 them such terms as " ganglion-cells," " ganglionic swellings," or 

 " nerve-ganglia." 



y. Arachnida. 



Sexual Organs of the Phalangidae.* — Dr. H. Blanc has studied 

 several points in the anatomy and physiology of these organs in 

 four species of Phalangium. In forming conclusions upon disputed 

 matters he has been careful to study the tissues in the fresh state, 

 when possible, so as to eliminate the possible evils attending the use 

 of reagents. 



The testis shows its primitively paired condition by being 

 made up of two lateral lobes connected by a strongly constricted 

 bridge of tissue ; an efferent duct issues from the apex of each of 

 the two forwardly directed lobes, which become attenuated towards 

 this point. The ducts unite and form on the sternum a knot in 

 which the vas deferens originates, between the penial sheath and the 

 accessory generative gland ; their walls consist of an external pave- 

 ment epithelium and an internal layer of cylindrical cells which 

 probably supply a hyaline liquid to the sperm in its passage. Just 

 before entering the penis the vas deferens acquires a stout chitinous 

 lining and an external coat of obliquely concentric muscular fibres, and 

 the epithelium becomes very thin ; this layer almost disappears in 

 the fine prolongation which enters the penis, but the chitin persists. 



Near the apex of the penis are two oval chitinous disks, support- 

 ing an accessory gland, in Phalangium opilio and cornutum ; in 

 P. longijpes and rotundum the gland is in immediate contact with the 

 posterior section of the penis ; P. longipes is also remarkable for 

 having a sac-like diverticulum of the chitinous layer of the middle of 

 the penis, forming a kind of sheath to that organ, and surrounding it 

 as far back as the origin of the terminal gland ; the sac is longitu- 

 dinally divided into two smaller divisions by a fold of chitin ; these 

 divisions contain what is apparently an albuminous secretion, and 

 they probably constitute an accessory generative gland. In all the 

 species the posterior end of the penial chitinous sheath, which is 

 single, bears a ridge or fold to which the protractor muscles are 

 attached, and from which they pass to the sides of the body. The 

 glands already mentioned as opening near the end of the penis also 

 occur in the female, and are probably brought into use during 

 copulation. 



The testis is covered by a very delicate tunica propria consisting of 

 pavement epithelium ; but the muscular fibres which usually underlie 

 this layer in the Arthropoda, appear to be absent, and it is consequently 

 in direct contact with the internal epithelium ; this epithelium consists 

 of (1) the true epithelial cells, which are polygonal, with cell-wall, 

 clear protoplasm and granular nucleus, united in groups of six to eight, 

 and (i!) of smaller cells intercalated between the former in groups of 



* Bull. Soc. Vaud. Sci. Nat., xvii. (1880) pp. 49-73 (3 pLs.). Cf. this Journal, 

 iii. (1880) pp. 248, 423. 



2 H 2 



