153 Dr. A. Krohn on the Male Generative Organs o/Phalangium. 



These two glands also occur in the females ; but even when 

 their pregnancy is very far advanced, the size of these glands is 

 less than in the males. In their structure they differ from those 

 of the males only in the circumstance that the spiral filament 

 appears to be entirely wanting in the ramifications, although 

 present in the main ducts. The spot at which the two main 

 ducts discharge themselves corresponds exactly with that of the 

 male. Their orifices are also in the vicinity of the sexual orifice, 

 upon the upper wall of the sheath embracing the laying-tube*. 



As to the use of the secretion of these glands nothing can at 

 present be stated with certainty. In the male, the secretion is a 

 clear, tenacious, thickly fluid substance, apparently very similar 

 to the spinning-material of the Araneida. 



In conclusion, I must refer to an exceedingly remarkable 

 phenomenon which I have observed in the examination of nearly 

 all males of P. opilio-\. This is nothing less than a production 

 of eggs from the testis, at the same time that the development 

 of the semen is by no means diminished. The number of ova 

 produced by the testis may sometimes be so great that, as in 

 the ovary, they occupy the entire surface ; or it may be very 

 small, and in this case the ova occur only on particular spots of 

 the testis. In the former case the ova, as on the ovary, present 

 the most various states of development, from the smallest, with 

 the vitellus still clear, to those in which the vitellus appears 

 more or less turbid. These ova, however, appear never to attain 

 the full size of those produced on the ovary. I have only ob- 

 served one case in which, among a number of ova, two or three 

 were remarkable for their preponderant size. These ova agreed 

 perfectly with the nearly mature ovarian ova, not only in their 

 size, but also in the nature of the vitellus, which appeared of a 

 chalky whiteness. In a second species (which, from the form 

 of the penis, appears to be the one investigated by Treviranus 

 and Tulk), the males of which I was able to procure much more 

 frequently, I have rarely detected ova upon the testis, and when 

 present they were always but little developed. 



To remove the suspicion that I may perhaps have erred in 



* I may remark here, in passing, that the two supposed caecal tubes ex- 

 tending to the laying-tube, which Tulk has regarded as cement-glands, are 

 really nerves, as has already been indicated by Gegenbaur (GrundzUge der 

 vergl. Anat. p. 276). I have succeeded in tracing them to their origin in 

 the thoracic ganglion. They also occur, although of less size, in the male, 

 in which they accompany the portion of the vas deferens issuing from the 

 coil to its immersion in the penis. In both sexes they supply the retrac- 

 tors of the copulatory organs, and also penetrate with a portion of their 

 branches into the interior of the latter, and then become further divided. 



t The males of this species are exceedingly rare in comparison to the 

 females. 



