OBSERVATIONS ON VAUIOUS SPOROZOA. 297 



logical knowledge, and has closely studied the effects of the 

 parasites on their hosts, — or, in other words, their pathological 

 effects. Since Dr. Pfeiffer has most kindly given me many 

 beautiful preparations of Sporozoa belonging to this and other 

 groups, I have been able to study, and, I may add, to confirm 

 his results. 



With regard to the Myxosporidia, the description of the 

 epidemics they have caused from time to time in some of the 

 rivers of Germany forms a most interesting part of Dr. 

 Pfeiffer's work, and is worthy of the close attention of 

 pisciculturists. Barbel, pike, and perch were chiefly attacked. 

 "The sick barbel present a striking appearance from the 

 presence of discoloured tumours in the skin, and of deep 

 crateriform ulcers on the head, the hinder part of the body, 

 and the tail : the ulcers have a widely infiltrated base.^' Fig. 

 22 shows part of one of Dr. L. Pfeiffer's sections of a myxo- 

 sporidial tumour of a barbel. The growth is alveolar in 

 structure, the alveolar walls being composed of fibrous tissue. 

 The contents of the alveoli consist solely of parasites. In 

 the upper part of the figure is a portion of the periphery of a 

 reticulated parasite from which sporocysts have separated ; at 

 the edge of the parasite is a nuclear spindle. The thread-cells 

 of the sporocysts are stained deeply. Some of the sporocysts 

 are devoid of definite characters j whether they are young 

 forms, or residua after the escape of the single amoeboid spores, 

 is a question I have not been able to determine. L. Pfeiffer 

 shows that these tumours begin as an infection of striped 

 muscle-fibres, and some of the preparations demonstrate this 

 point most distinctly, the young parasites in all stages of 

 existence being visible within muscle-fibres at the periphery 

 of the tumour. 



Writing of the effects of Sarcosporidia, Leuckart has said, 

 " Although the tubes occasionally occur in immense numbers 

 close to one another, so that the flesh looks as if half of it 

 consisted of psorosperm tubes, yet they seem usually to cause 

 no special uneasiness. In many cases, however, the phenomena 

 of paraplegia, retarded respiration, and even suffocation, are 



