512 POPULAR SCIENCE MONTHLY. 



tially of those characters physical and mental which the individual in- 

 herits from its male parent; as the nucleus of the ovum must be for 

 the female parent. In the series of divisions by which the fertilized 

 ovum separates into the cells which form the tissues of the body, the 

 material or chromatin of the fused nuclei is with the utmost exact- 

 ness divided equally to each, so that every unit of the system receives 

 its share of this chemical endowment. This much the study of struc- 

 ture has taught us. But to the chemist the ultimate explanation of 

 these processes seems to lie in the nature of the chemical substances 

 composing the chromatin. In the salmon the ova and sperm are easily 

 obtainable, and afford the unfertilized eggs and spermatozoa almost 

 free from admixture with other matter. Accordingly the methods 

 which Miescher employed for the separation of the constituents of these 

 cells were simple, yet yielded the material sought in quantity and 

 purity. The nuclei from the sperm proved to be composed mainly of 

 a peculiar compound or series of compounds of the nature of ethereal 

 salts. The acid radical was nucleic acid — a substance previously dis- 

 covered by Miescher in the white corpuscles of the blood of mammals; 

 the other component was an organic base which he called protamin. 

 To the question as it presented itself to Miescher's mind, whether 

 protamin may be regarded as the essential element in fertilization, the 

 answer must be in the negative. Miescher found that protamin is not 

 present in the sperm of the frog or the testes of a bull ; and subsequent 

 investigators have shown that it is absent even in some fishes. Yet in 

 these cases it is apparently replaced, and the same functions performed 

 by another substance of basic character known as histon. Miescher 

 was led by these facts to the view that there is no one substance which 

 can be regarded as the essential element in fertilization; but that 

 the chemical processes involved are probably a series of reactions. 



To attempt even an outline of the investigations and discoveries 

 to which Miescher's study of the chemistry of the cell has led, would 

 necessitate reviewing one of the most fertile fields of biological chem- 

 istry, and would involve much that is important in pathology as well. 

 rt is sufficient here to point out that what has been accomplished is 

 in great measure the ripening fruit of the seed planted by Miescher 

 in the quiet of his laboratory a generation past. In the final solution 

 of the profounder biological problems, these investigations on the 

 salmon and the researches to which they have led will probably be 

 found to have contributed in large measure toward that object, which 

 Miescher in one of his letters — almost the last before his death — ex- 

 pressed in the words — "There remains then this great question to be 

 fought out by the biologists of the future — Is it chemical composition 

 or cell structure to which we must look as the ultimate basis of vital 

 phenomena ?" 



