THE AMERICAN ENTOMOLOGIST. 



41 



are the first stages in the growth of toad- 

 stools, that is, Agarici and Polypori. 



Which of the above Dr. Hagen would 

 have us believe grows from the fly fungus 

 it is difficult to say. The fly fungus is a 

 species of the genus Saprolegnia, formerly 

 called Sporondonema, Empusa, or Achlya. 

 It consists of short jointed threads, two to 

 five millimeters long, growing from the body 

 of flies, usually in Autumn. These threads 

 enlarge in the outer end or last joint, which 

 becomes filled with swarm spores that as 

 soon as mature burst their envelope, move 

 about for a few hours, then come to rest, 

 generally near the parent filament and im- 

 mediately begin to grow. It has been 

 asserted hy some authors that this plant is 

 identical with the fish fungus, which de- 

 stroys eggs and young fish in fish-breeding 

 establishments. Other writers make sev- 

 eral species in this class of fungi, dependent 

 on variations in the form of the filaments 

 and peculiarities of the sexual organs. 

 The sexual characteristics of the Saproleg- 

 niese connect them more closely with Pero- 

 nospora or the rusts, such as cause the 

 potato disease, than with any other class 

 of fungi, but no one but Dr. Bail has yet 

 suggested a specific relation between them. 



We fear the observations of Dr. Bail 

 have not been made with such care as to 

 compel full credence. Dollinger and Drys- 

 dale have shown that the microscopic 

 monad has a cycle of growth as definite 

 and unvarying as any quadruped, and fungi, 

 in all their wonderful varieties of fructifi- 

 cation, do not pass certain well marked 

 limits of modification. The spores of Sa- 

 prolegniese and of numerous moulds are 

 continually floating in the air in larger or 

 smaller numbers according to the season, 

 and their development depends upon nice 

 conditions of temperature and moisture 

 that man cannot control. Supposing it 

 were possible to find a parasitic fungus to 

 attack the grasshopper, the conditions of 

 its growth must be provided, and we appre- 

 hend this would be impossible. 



The rarity of epidemics of fungi shows 

 how seldom all circumstances combine with 

 sufficient nicety to allow an injurious de- 



velopment. The "pebrine" of the silk- 

 worm must be regarded as the result of en- 

 feeblement of the constitution of the worms 

 caused by an artificial life. But Dr. Bail is 

 not alone in his views with regard to the 

 polymorphic development of microscopic 

 spores. Metcalfe Johnson in the Monthly 

 Microscopical Journal of 187 1, vol. 6, p. 

 217, describes with what appears to be 

 irrefragible precision and fullness of detail, 

 the development of moss (a mnium) from 

 monads. This is only one of several state- 

 ments affirming polymorphic development, 

 which do not yet receive much attention, 

 because of a conviction in the minds of 

 accurate students, that many of them assert 

 positively, what is yet doubtful, as regards 

 the extent oi variation. It often happens 

 that one species of fungus grows on another 

 without any but an accidental local relation 

 between the two, and it is in this way so 

 easy to be mistaken, that nothing but the 

 most careful and repeated observation will 

 establish a genetic connection between 

 forms so remote from each other in charac- 

 ter, as saprolegnia and yeast, and it is cer- 

 tain that these observations are yet to be 

 made. 



TWO VALUABLE INSECTICIDES. 

 London Purple.* 



This powder is obtained in the follow- 

 ing manner in the manufacture of aniline 

 dyes. Crude coal-oil is distilled to pro- 

 duce benzole. This is mixed with nitric 

 acid and forms nitro-benzole. Iron filings 

 are then used to produce nascent hydro- 

 gen with the excess of nitric acid in the 

 benzole. When distilled, aniline results : 

 to this arsenic acid, to give an atom of 

 oxygen which produces rose aniline, and 

 quicklime are added to absorb the arsenic. 

 The residuum which is obtained by filtra- 

 tion or settling is what has been denomi- 

 nated " London Purple," the sediment 

 being dried, powdered, and finely bolted. 

 The powder is, therefore, composed of lime 

 and arsenious acid, with about 25 per cent. 

 of carbonaceous matter which surrounds 



* From advance sheets of Bulletin No. 3 of the U. S. Ento- 

 mological Commission, by C. V. Riley. 



