54 Prof. M'lntosh's Notes from the 



a mass into the water, and then slowly mixed with it. In 

 the experiments made in the laboratory the smallest trace of 

 milt fertilized every egg in the vessels, which were about a 

 foot across, so that the activity of tlie sperms was charac- 

 teristic. The quantity of ripe ova discliarged at a given time 

 was quite as large in proportion as in the plaice, in the turbot, 

 and in the flounder. Fishes in which the testes are small, as 

 in the torsk, plaice, long-rough dab; and sole, do not appear 

 to differ much, in regard to the rapidity of issue of the ripe 

 eggs, from those with large testes. The small size of the 

 testes in the horse, compared with the large size of the testes 

 in the porpoise, is another instance of the caution requisite in 

 drawing conclusions on this head. At any rate, in regard to 

 fishes the ascertained facts up to date do not seem to warrant 

 strong statements on the subject. The ripe female sole in 

 Scottish waters discharges a considerable number of eggs, and 

 a large number are also emitted by the ripe lemon-dab. The 

 quantity of ripe eggs which issue from a torsk is about as 

 large in proportion as in a cod, yet the testes of the two differ 

 much in size. 



The egg of the long-rough dab, on issuing from the oviduct, 

 is beautifully translucent, and measures from r0668 to 1''1430 

 millim. The zona radiata clings somewhat closely to the 

 contained yolk, and is wrinkled all over, quite as much as in 

 the lemon-dab. The perivitelline space is small, and thus 

 differs from the condition as ordinarily seen in the tow-nets. 

 As a rule the yolk, or egg proper, has a diameter of 1'0668 

 millim., while the capsule has a diameter of 1-1430 millim. 

 When placed in sea-water, and whether fertilized or not, a 

 gradual change takes place in the perivitelline space, so that 

 next morning, that is, in twelve hours, the diameter of the 

 capsule is from 1-7907 to 1-8669, probably by the imbibition 

 of water, as in the case of desiccated eggs, while the diameter 

 of the egg proper in the centre remains nearly the same. 

 This distention removes many of the wrinkles from the sur- 

 face, but not all, since these were visible in almost every 

 example np to the period of hatching. Many of the eggs had 

 groups of minute fatty granules dotted all over the yolk. 

 Next day (22nd March) at 12.30 considerable progress had 

 been made, the disk being in the multicelled condition, the cells 

 of the blastoderm being often prominent, and at 5.40 P.M. 

 much more finely dividexl. The minute granules of oil occur 

 over the yolk, beneath the protoplasmic investment, and they 

 appeared to be fewer next day, so that probably they were 

 gradually used up in the process of development. The 

 minutely cellular disk presents an inward curvature at its 



