KOLLIKER, ON VEGETABLE PARASITES. 171 



worm, which becomes fully developed in the intestinal canal 

 of many warm-blooded animals, both mammalia and birds ; 

 amongst which are enumerated the dog, cat, pig, sheep, 

 mouse, man, and the common fowl. The Trichina attains full 

 sexual maturity in about two days after its introduction into 

 the intestine. It is viviparous, and the minute filaria-form 

 embryos which are produced in about six days more, imme- 

 diately commence their migration by penetrating the walls 

 of the intestine, in order to reach the striped muscular tissue. 

 The greater part of the embryos remain in the muscles 

 immediately surrounding the visceral cavities. They make 

 their way through the intermuscular connective tissue, but 

 ultimately penetrate into the interior of the muscular fasciculi, 

 where they reach, in about fourteen days, the size and assume 

 the structure of the well-known Trichina spiralis. It would 

 appear also that the immigration of the young Trichina in 

 great numbers may cause very serious symptoms, either from 

 peritonitis caused by their passage through the walls of the 

 intestine, or great debility in consequence of the disintegra- 

 tion of the muscular tissue. 



On the frequent Occurrence of Vegetable Parasites in 

 the Hard Tissues of the Lower Animals. By Prof. A. 

 Kolliker. 



(Abstracted from the 'Zeitsch. f. Wiss. Zoolog.,' vol. x, p. 215; 1859.) 



In examining the scales of Beryx ornatus, Ag., from the 

 chalk formation in England, I noticed peculiar tubular 

 structures, presenting an elegant stelliform figure, of which 

 I was at first at a loss what to make. Their similarity 

 in form to pigment-cells led me at first to think they 

 might be of that nature, but this idea was abandoned when 

 I found that the structures in question occurred not merely 

 in the external layers of the scales, but in the interior as 

 well. At the same time I was unable to entertain any 

 other supposition, since the structure exhibited no points of 

 resemblance with any of the known forms of tubular and 

 cellular structures of bones and scales. 



Shortly afterwards, on proceeding to the investigation of 

 the skeleton of the stony Corals and Sponges, I was again 

 struck with the occurrence of curious elongated, delicate 

 systems of canals, the further examination of which soon 

 opened my eyes, and finally led to the conviction that in all 

 those cases the appearances were due simply to the presence 



