l6o THE EVOLUTION OF SEX. 



recent concentration of attention upon the nucleus has not led to some 

 under-appreciation of the general protoplasm. In the permanent conjuga- 

 tion of two cells, the entire contents of the two cells are obviously fused ; 

 and even when the union is temporary, Joseph has observed what looks 

 like an interchange of protoplasmic as well as of nuclear substance. 

 (/') There are a few observers still, such as Kussbaum, who maintain 

 that in fertilisation in animals the substance of the sperm is important 

 as well as its nucleus. {c) Strasburger notes the minimal quantity of 

 cell-substance so often present round the male nucleus, and urges that 

 if it were important there would surely be more of it. But it is quite 

 conceivable that a minimal quantity of highly active protoplasm might 

 have, like a ferment, a momentous influence on a large quantity of a 

 different character, {d) The researches of Boveri show, that though the 

 union of nuclei is so essential, the protoplasmic activity and share in the 

 process are also considerable. It appears to us a fact well worthy of con- 

 sideration, that according to this authority the sperm brings with it into 

 the ovum a protoplasmic centre — a " centrosoma '"' — which appears to be of 

 much importance in the preparation for division. In this preparation, 

 according to Boveri, the "muscular fibrils'"' of a special kind of protoplasm 

 (or archoplasma) literally move the nuclear elements. ' ' The movement 

 of the elements is wholly the result of the contraction of the attached 

 fibrils, and the final arrangement of these nuclear elements in the ' equa- 

 torial plate ' is the result of the action of the archoplasmic sphere exerted 

 through the fibrils." Xow this specially active protoplasm, which thg 

 skilful observer seems to have succeeded in fixing, has its centre. There 

 are two central corpuscles, each " ruling a sphere of archoplasma." Where 

 then do these centres come from ? " It is probable," Boveri says, " that 

 the spermatozoon brings a centrosoma into the ovum, and that this by 

 di\dsion forms two centres. Since these two corpuscles condition the 

 di\'ision, the dependence of this upon the presence of the spermatozoon 

 is for the Ascaris ovum explained." We have given these details, technical 

 as they are, because they seem to us to show clearly that it is rash to 

 deny that even the minimal cell-substance of the spermatozoon may, as 

 well as its nucleus, have a momentous influence in fertilisation. 



§ 3. Physiological Theories of Fertilisation. — The mor- 

 phological facts, estabhshed and verifiable by observation, form 

 the basis from which to attack the deeper problem of the 

 physiology of fertihsation. Here experiment is almost insuper- 

 ably difficult ; only a few incidental results are as yet available ; 

 the suggestions thrown out by various naturalists must therefore 

 be appreciated according to their consistence with the general 

 principles of physiolog};, and with the general theory of sex 

 and reproduction. To some they may still appear a page of 

 probabilities. 



Sachs compares the action of the male element upon the 

 egg-cell to that of a ferment. De Bary also suggests that pro- 

 found chemical differences exist between the two elements. 

 A'ery suggestive is the view of Rolph, who regarded the process 



