INDUSTRIAL PROGRESS DURING THE YEAR 1875. cxlvii 



Professor Leidy has recently called attention to the para- 

 site that lives in the proboscis of the house-fly, a thread-worm 

 Filaria muscce first discovered by the well-known natu- 

 ralist Mr. J. H. Carter in the house-fly of India. Dr. Leidy 

 found it in numbers from one to three in about one fly in five. 

 Dr. Diesing has referred the parasite to a new genus, with 

 the name Habronema muscce. The singular position in which 

 the worm lives suggests that there are many unsuspected 

 places in which we may have to search to find the parents 

 or offspring of our own parasites. 



In a communication to the French Academy in Novem- 

 ber last, M. Duval, calling attention to a former paper in the 

 Journal de VAnatomie, September, 1874, states that he has 

 found a means of explaining both the doctrines of the pan- 

 spermists and the heterogenists. The explanation lies simply 

 in the statement that he has discovered that the various so- 

 called minute organisms (such as ferments) are simply one 

 and the same organism, which has the power of becoming 

 differently developed. He asserts that he has proved by 

 experiment that the transformation of yeasts is possible, and 

 that the specificity of action of different ferments is a purely 

 relative phenomenon, dependent rather upon the composition 

 or the state of the media than upon the proper constitution 

 of these same organisms. 



For ten years after the publication of Ehrenberg's " Infu- 

 sionsthierchen," it was supposed that the Rotifera were all 

 hermaphrodites. In 1845 Mr. Brightwell discovered a roti- 

 fer with separate sexes in the genus Asplanchna; in 1850 

 Mr. Gosse discovered the male of another species of the same 

 genus, and in 1854 Dr. Leydig that of a third. Two years 

 later Mr. Gosse figured in the "Philosophical Transactions" 

 the males of several species of Brachionus, Polisarthra, Syn- 

 chceta, and Saeculus. More recently Dr. C. T. Hudson has 

 discovered the male of Pedalion minim. Previously to this 

 discovery it will be noticed that the others belong all to one 

 group the free swimming rotifers ; and this caused Professor 

 Huxley to consider the Motif era as permanent forms ofechi- 

 noderm larval, and his argument was hard to answer, for it 

 rested on the supposed monoecious character of some of the 

 largest and most common rotifers creatures constantly 

 watched and studied in consequence of their great size and 



