458 Prof. J. C. Ewart. On the Natural and [Mar. 27, 



sea-firs and sea- weeds in exactly the same way as she does among 

 stones. On each stem of the colony there is a cluster of ova about 

 the size of a small grape, and all the clusters had reached, on arrival, 

 the same stage of development as if they had been deposited about 

 the same time and by the same fish. It is easily understood how 

 such clusters may be formed if the female is almost in contact with 

 the stems, and there is nothing easier than to form such clusters 

 artificially ; the first eggs adhere to the stem, then the others adhere 

 to the eggs already deposited, but being heavy, some of them roll 

 over to the under aspect so as to form the lower half of the sphere, 

 and the result is that partly, it may be owing to the stems moving 

 slightly, there are as many eggs on their under as on their upper 

 surface. It would, however, be extremely difficult to understand 

 how such clusters or how conical masses could be formed on stones 

 if the eggs fell several fathoms before reaching the bottom. 



This method of depositing and fertilising the eggs accounts, I 

 think, for all the eggs, or, at least, for a very large percentage of 

 those found attached to sea-firs, sea- weeds, and stones, containing 

 developing embryos. 



III. Experiments made as to the Deposit and Fertilisation of the Eggs. 



When a female was depositing her eggs she was very easily dis- 

 turbed ; whenever anything was introduced into the tank she at once 

 darted off. When strong currents were made she at first seemed to 

 apply herself nearer to the bottom to make sure, as it were, that the 

 spawn would get fixed before it could be carried aw T ay ; but when the 

 currents were further intensified, she at once changed her position 

 and arrested the escape of the spawn. 



A spawning female was held immediately under the surface of the 

 water so as to cause the spawn to escape. When this was done it 

 escaped in long xibbons consisting of a single row of eggs. So firmly 

 do the eggs adhere to one another, that in perfectly still water the 

 ribbon was sometimes over a foot in length before it broke. When 

 it had only about 2 feet of water to travel through it fell in wide 

 loops at the bottom, but when it had over 3 feet to fall the chain 

 broke up into numerous segments which formed an irregular pattern 

 on the bottom. From experiments made it seems the further the 

 eggs have to fall, and the longer they are in contact with the water 

 before they reach the bottom, they are more widely dispersed, and 

 have all the less adhesive power.* When the eggs are expressed in 

 water moving rapidly in various directions the chains soon break into 

 short segments, and the individual eggs and the small groups are 



* It may be mentioned that herring eggs if kept moist are still slightly adhesive 

 24 hours after they are shed. 



