[7] RETARDING DEVELOPMENT OF SHAD EGGS. 801 



for the ordiuary purposes of transport-ation from the spawning grounds 

 remote from the hatching stations. An important matter to attend to in 

 the application of the above plan will be to effectively scald the cloths 

 which are laid in the trays each time before they are again used, or else 

 they will become the nidus of untold myriads of putrefactive germs 

 which will lodge from the air in dust, and the retention and develoj>meut 

 of which would be favored by whatever of mucus, dead eggs, egg-mem- 

 branes, and blood might adhere to the cloths from one time to another. 



The putrefactive germs always liable to be conveyed in the impalpa- 

 ble dust constantly suspended in the air of houses in this latitude are 

 consequently much more insidious in their approaches than the germs 

 or spores of the saprolegnious faugus, which ordinarily causes a considera- 

 ble loss of eggs in the hatching-cones. The eggs attacked by the fungus 

 in the water first turn white; the egg-membrane then shows a disposi- 

 tion to wrinkle or become flaccid; the mycelium or growing stage of the 

 fungus is now in active progress. The mycelium is simply a felted mesh- 

 work of branching fungus cells, which appropriates the substance of the 

 egg and completely envelops its membrane. In this (,stage it is com- 

 paratively harmless. Afterwards from the felted mycelium threads club- 

 shaped cellular prolongations grow out, which radiate in all directions 

 like the seeds on a dandelion seed-head. In time each one of these club- 

 shaped heads of the fungus, to the number of hundreds on every alfected 

 f^gg, develop a large number of spores or germs on the inside ; directly 

 the end bursts open and the minute spores swarm out of the club-shaped 

 spore-case in great numbers. Each of the spores is capable of independ- 

 ent movement by means of long vibrating filaments attached to it at one 

 end. These wander about in the water, lodge on healthy eggs, and grow 

 on and destroy them, so it is important that infested eggs should be 

 removed as soon as they make their appearance in the hatching appa- 

 ratus. Kiihue and Cohn have shown, however, that a temperature of 

 140° F. is sufficient to kill the germs of Bacteria and other putrefactive 

 organisms, and it is very likely that such a temperature or less than the 

 boiling point of water, 212° F., would be quite sufficient to clear off and 

 kill uny fungus germs which might adhere to the pans, trays, and cloths 

 used in the transportation of ova. 



The preceding account of the development, destructive growth, and 

 maturation of the spores is from personal observations made on eggs 

 infested with fungus in the hatching-cones on the barges at Havre de 

 Grace in 1880, and it is only introduced here to direct attention to some 

 possible means of staying or mitigating its ravages. I do not pretend 

 to know the species by its botanical name. I leave its identification for 

 the cryptogamic botanists; practically a knowledge of its life-history 

 sutfices for our purposes. 



The following record of the most salient features of my observations, 

 made in association with Colonel McDonald, is on the whole not as en- 

 couraging as the experiment made at Havre de Grace, Md., but it is of 

 S. Mis. 110 51 



