262 APPENDIX. 



with a double contour. Moreover, externally they are single in 

 their course and of the same size, the caules sometimes being 

 covered at their terminations with small, thorny-looking ex- 

 crescences, which Pacini incorrectly supposed to be radicles. 

 Near the capitulum (at the point j) the stalk is surrounded by a 

 species of sheath (analogous to a perianth), and the individual 

 spores are separated from one another. Besides the diameter of 

 the caulis varies with the size of the specimen, in A the diameter 

 is 0'013 mm. So it is with the cavity of the stalk, which in A 

 is 0-008 mm. In general the length of the stalk depends on its 

 development ; in A and B it \vas about O770 mm. long. Pacini 

 has drawn the stalk shortened one half, but I have given the 

 stalk and capitulum of the natural proportion. The mycelium 

 consists of that structure which Pacini again gave at K, and in- 

 correctly described as an alga, but Robin rightly interpreted it. 

 The ramifications of the mycelium one sees at M and L. There- 

 fore these rows are formed on elongated and reunited cells, and 

 exhibit internodes. Those containing in them small dark cells, 

 but which are not spores, as Pacini would have it, have a diameter 

 of 0'0015 mm. Sometimes the tubes bend themselves angularly 

 and return back towards the epithelial cells, caules, and spores. 

 After two months' preservation in solution of gum arabic with 

 a little arsenious acid, Pacini found nothing more of the 

 substance here described as mycelium, while all the other parts of 

 the fungus had been very well preserved. Has Pacini here 

 committed an error in observation, or has he overlooked 

 altogether the mycelium ? 



The treatment consists not in dropping in acetate of lead, as 

 Robin repeats, but in vigorously injecting water. The acetate of 

 lead should be employed secondarily against the Otorrhceq which 

 remains behind. 



In regard to the position of Pacinr's fungus in the system, I 

 should not after my observations of Pacini's drawings have 

 placed it with Aspergillus, as Robin did, but associated it with 

 Sluyter's Mucor mucedo, so long as we in general allow, that 

 every observer accurately observes, and has given drawings true 

 to nature. The differences between Aspergillus and Mucor 

 mucedo consist for the present in the dissimilar form of the so- 

 called placenta and the filamentary radiated or homogeneous 

 light simple ring forming the periphery of the capitulum, and 

 these are possibly only differences in the age and maturity of the 

 individual specimens. (See page 271). 



