90 Mr. E. Ray Lankester's Zoological Observations 



for the ovaries, which they actually located beneath the skin ; 

 this view I must most fully oppose, as a special study of the 

 integument of Sipuncidus has shown me what structures these 

 authors have mistaken for ova. Others, again, have taken the 

 strange little diverticulum of the intestine placed near the rec- 

 tum for the ovary, but without oifering proof. I have yet a 

 new view. I consider that the " bush-like processes " de- 

 scribed by Keferstein and Ehlers as occurring on each side of 

 the rectum are the ovarian villi. These arborescent tufts are 

 outgrowths of the cellular peritoneum and enclose the ova, 

 which become detached when very small (^irW inch), either 

 in groups or singly, ensheathed in a portion of peritoneum, 

 and proceed to grow to full size in the perivisceral liquid. The 

 proof of this is in the structure of the villi, and in the structure 

 of floating masses of minute ova occasionally to be found in 

 the perivisceral liquid. The ova are detached from the villi 

 probably at cei'tain seasons and as soon as developed ; hence 

 I have never found the villi containing unmistakable ova, 

 when attached in place on the rectum. 



The mulberry spheres are certainly not, as supposed by Brandt, 

 testicular. They have not the structure of such testicular mul- 

 beny masses in Annelids ; for in these of Sipmiculus I have 

 made out what Brandt does not describe, viz. a membrane with 

 a distinct nucleus enveloping the aggregated spherules. They, 

 I believe, give rise to the abundant pink corpuscles of the peri- 

 visceral fluid, and are, like the " Topfchen," detached from the 

 tentacular vessels originally. The true testis is still an open 

 question. I found that the curious little diverticulum of the in- 

 testine in several specimens examined in March had become 

 greatly dilated, attaining a full inch in length ; and it was filled 

 with a creamy fluid in which were a dense mass of motile fila- 

 ments. It is possible that these were bacterioid parasites, but 

 most unlikely when they recur in eight individuals examined 

 within two days. There were further appearances of the develop- 

 ment of these vibratile rods which tended to confirm the notion 

 that the wall of this diverticulum of the intestine becomes the 

 testis. On the other hand the structure of the gi'eat brown pair of 

 tubes was very carefully studied ; and I found that they develop 

 in their walls innumerable corpuscles which in spring (May) 

 take quite the form of the Mammalian spermatozoon, and abound 

 in immense number in the liquid filling the brown sacs. The 

 balance of evidence is on the whole in favour of the brown 

 tubes being testes. At the same time let me mention that 

 they become much dilated in May, and take into their cavity 

 large quantities of the perivisceral fluid, and with it the floating 

 ova, or the mulberry spheres, if they are present. 



