8 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



in its properties from the egg mother-cell which left the ovary, in that 

 it is now a germ capable of further development into a complete organ- 

 ism. This process also could not be studied in the living mackerel egg, 

 but probably does not there differ from what has been observed in the 

 Spanish mackerel egg. 



The spermatozoan of the mackerel consists of a pear-shaped head 

 about 0.002 mm. in length, with a short rod-like middle piece attached 

 like a stem to the narrow end of the pear, and bearing an exceedingly 

 delicate flagellum or tail which is about 20 to 25 times the length of 

 the head. When fully ripe, the sperm is quite fluid and mixes readily 

 with sea water, through which the spermatozoa, by their very active 

 lashing, quickly become disseminated. Under such circumstances, a 

 very small quantity of sperm will serve to impregnate a great many 

 eggs, and it is of practical importance to use as small a quantity as 

 will effect the purpose, to the end that the eggs do not become clogged 

 with great numbers of spermatozoa, which will adhere to their mem- 

 branes and interfere with free respiration. With fresh and perfectly 

 ripe sperm, the egg of the mackerel is very easily fertilized, even those 

 eggs which exhibit a considerable degree of opacity, and are hence 

 supposed to be less mature, responding at once to the presence of 

 spermatozoa. In fact, even when considerable numbers of eggs, sev- 

 eral hundreds of thousands, were handled, scarcely any would be 

 found to be unfertilized, and in no case, except when the sperm or ova 

 were obviously immature, did as many as 1 per cent fail of impregna- 

 tion. This ease of fertilization and the almost perfectly uniform way 

 in which the eggs would subsequently develop, all of them passing 

 into the same stage at nearly the same moment, seem to me to indicate 

 their healthful state and the necessity of seeking the cause of the 

 failure of the hatching operations in some condition subsequent to this. 



It is, of course, impossible, from the study of a relatively small lot 

 of material obtained under only one set of conditions, and with no 

 means of checking results by making comparisons, to state positively 

 that the eggs were in the best vital condition, but the uniformity and 

 regularity of results and the comparative scarcity of abnormalities, 

 except those mentioned later on, seem to lead to this conclusion. My 

 experiments to test the length of time during which the spermatozoa 

 retained their fertilizing powers failed, owing to the accidental impreg- 

 nation of the entire lot of eggs reserved for this purpose, and sub- 

 sequently no opportunity for repeating the experiment was found. 

 Direct observation, however, on sperm placed in pails or jars of water 

 showed that the spermatozoa lost their activity completely in 45 to 60 

 minutes, and this period must consequently be admitted to be the 

 extreme limit of their vitality under the conditions of the experiment. 

 I would here point out the futility of hoping for any better results 

 through the substitution of the so-called dry method for the wet method 

 of fertilization. The former was invented to meet certain peculiar 

 conditions, and is indicated in cases where the contact of water with 

 unfertilized eggs causes either the formation of a coat impervious to 



