1883.] 



MICROSCOPICAL JOURNAL. 



223 



the yeast-plant is a condition of Feni- 

 cilliutn. The sporules of yeast, under 

 certain conditions, elongate and grow 

 into filaments, which may be the same 

 as the mycelium of PeniciUium grow- 

 ing submerged. 



Fungi of various kinds may be found 

 in the fall upon leaves of many plants, 

 and especially upon fruits, such as 

 grapes, apples, peaches, etc. These 

 may be cultivated in the manner al- 

 ready described, and will afford inter- 

 esting objects for study during the 

 winter months, as they may be kejDt 

 dormant for months, until warmth and 

 moisture quicken them into life. 



The Fresh-water Medusa. 



We present our readers this month 

 with an illustration of the beautiful 

 fresh-water medusa which was found 

 some time ago in the Victoria Regia 

 tank of the Botanical Gardens, Lon- 

 don. This delicate organism, the 

 only one of its kind found in fresh- 

 water, has been very abundant in the 



The method is to plunge the creatures 

 into a solution containing four grains 

 of corrosive sublimate dissolved in a 

 pint of water, the solution being 

 maintained at a temperature of 85 ° F. 

 The bodies are rendered opalescent, 

 but the minute details of their struc- 

 ture are clearly shown in the pre- 

 served specimens. 



We have seen some specimens of 

 this medusa which appeared to be 

 well preserved, but it was said they 

 were killed with osmic acid. Possi- 

 bly this was a mistake, and that they 

 were prepared by Mr. Squire's method. 

 They were certainly good prepara- 

 tions, however made. 



The Microscopical Discrimination 

 of Blood. 



By C. M. Vorce. F. R. M.S. 



In the September number of this 

 Journal, editorial comment was made 

 upon the claim of some observers to be 

 able to discriminate human from other 



Fig. 42. — Fresh-water Mbdusa. 



tank this year. The water of the 

 tank, which sustains tropical vegeta- 

 tion, has a constant temperature of 

 85 ° F., and at this temperature the 

 great water-lily, from which the tank 

 takes its name, grows luxuriously. 



The first figure (fig. 42) shows the 

 medusa {Lii7inocladium Sotvcrbii) as it 

 appears while freely swimming. The 

 two succeeding figures represent the 

 same animal preserved by a method 

 employed by Mr. P. Squire, F. L. S., 

 and given in full in the Jou)-nal of 

 the Royal Microscopical Society. 



other mammalian blood, by measuring 

 the corpuscles soaked out from a dried 

 blood-stain, and stress was laid upon 

 the necessity for extreme caution in 

 reaching and announcing a conclusion 

 in such cases. 



Probably no microscopist, of more 

 than limited experience, needs any 

 reminder of the necessity of care and 

 caution in such cases, but from con- 

 siderable observation, and from the 

 published results of work by many 

 observers in the direction indicated, I 

 cannot escape the conviction that few 



