500 



SEMEN. 



staff, in the interior of which the spermatozoa 

 are developed, is the produce of the metamor- 

 phosis of this cell ; a metamorphosis which 

 here appears in its extreme form, but which 

 in other cases is less striking, and may even 

 be entirely wanting. Arid then it is the cell 

 in its unchanged form which appears as the 

 vesicle of developement of the spermatozoa. 



Under such circumstances it might for the 

 present be venturing too much to sever the 

 mode of developement of the spermatozoa in 

 the Decapoda, as a particular form, from 

 the ordinary endogenous formation of these 

 elements. We are not justified in so doing, 

 until we have proved that in other animals 

 mere nuclei exist as the mother cells of the 

 spermatozoa. It is possible that such a proof 

 may yet be established, indeed even probable, 

 when we consider that there is also in other 

 respects a difference in the formation of the 

 seminal fibres between the Decapoda and 

 other animals, inasmuch as the vesicles of 

 developement in the former generally and 

 almost constantly produce a greater number 

 of spermatozoa, whilst in other animals they 

 only produce a single fibre. 



As a circumstance of subordinate import, 

 which need not influence our judgment re- 

 specting the nature of the vesicles of de- 

 velopement, we may specify a difference in 

 the histological characters of these parts, 

 which certainly at first sight must appear 

 very striking. We meet with them either in 

 an independent free state, or separate, or en- 

 closed in a variable number within cells, 

 which themselves not unfrequently hang to- 

 gether in groups, or are even situated in a 

 cyst-like enclosure. But all these differ- 

 ences result solely from a different develope- 

 ment and application of all the plastic capa- 

 cities inherent in the cells. They are due 

 to the occurrence of an endogenous multipli- 

 cation, and are readily explained by the in- 

 timate unity and connection which this 

 method of developement presupposes. 



The formative elements of the semen ap- 

 pear to us in their primitive form as simple 

 nucleated cells. But it is only rarely that 

 they retain this original form. As a rule 

 they present only, the starting point of a 

 series of metamorphoses, which essentially 

 are limited to a new formation of nuclei, or 

 even of perfect nucleated cells in the interior 

 of the primitive spermatic cell : a new form- 

 ation, which, however, not unfrequently oc- 

 casions the destruction of the mother cell. 



It is not yet decided in all cases in what 

 manner the formation of the daughter cells 

 takes place, whether in the usual mode of 

 endogenous cell formation, or by enclosure 

 of portions of the contents. It seems, how- 

 ever, that the former mode of production 

 is by far the more frequent one. Reichert 

 has been the only one who has hitherto dis- 

 covered a formation of daughter cells round 

 portions of the contents (like the forma- 

 tion of cells in the minutely divided yolk) in 

 the spermatic cells of the Nematoda. If such 

 discovery should be confirmed should it 



even have a greater extension we may 

 then further presume (as Kolliker already 

 observes) that these two modes of develope- 

 ment are not essentially different from each 

 other. 



The description we have just now given 

 may, at all events, be sufficient to prove of 

 what a merely subordinate significance are 

 these differences in the histological arrange- 

 ments of the formative elements in the seminal 

 fluid. By a series of intermediate stages, we 

 can almost every where readily trace the con- 

 nexion in which the arrangement of the vesi- 

 cles of developement stands with the simple 

 primitive spermatic cell. Such a relation, 

 however, is not only interesting on account of 

 its enabling us to recognise an internal typical 

 structure and developement of the seminal 

 contents, and that in spite of their external 

 variety, but also because we thereby discover 

 that the primitive form of the male procrea- 

 tive elements is precisely the same namely, 

 a simple cell as that of the female gene- 

 rative product, which is designated " the 

 ovum." 



Having thus, by our preceding researches, 

 arrived at the result that the developement of 

 the spermatozoa always and everywhere ori- 

 ginates from the same primitive formation, 

 namely, from the simple cell, another question 

 now arises, viz. the question respecting the 

 relation of this simple cell to the epithelial 

 lining of the seminal tubes. 



This claims our attention the more, as our 

 conception of the epithelium, within a re- 

 cent period, begins to be more and more 

 indefinite, owing to the accumulation of ob- 

 servations, by which the so-termed epithelial 

 cells of the glands have been proved to be 

 mere vesicles of secretion, the workshops for 

 the preparation or expulsion of the 'products 

 of secretion. 



The recognition of the connexion of the 

 spermatic cells with the real epithelial cells is 

 rendered very difficult by the various meta- 

 morphoses of the former in the tubuli 

 seminiferi. Nevertheless, some observations 

 that have been made may perhaps already 

 justify the inference that the simple spermatic 

 cells are, in many instances, at least, identical 

 with the so-called epithelial cells of the se- 

 minal tubes. 



This appears with particular distinctness in 

 the Gasteropoda, in which Meckel* and Kol- 

 HJfcr have already assumed such a relation, 

 without, however, pronouncing it with that 

 degree of certainty which our observations 

 enable us to do. We may as readily con- 

 vince ourselves of this fact in the Annelida, 

 in Hirudo or Ascaris, as also in the In- 

 sects, Spiders, and Arthrostracans : it being 

 evident in all of them that the spermatic 

 ceils constitute the only vesicular contents 

 of the testicles, and form, in their primitive 

 shape, a complete epithelial layer, the ele- 

 ments of which frequently even assume a 

 polygonal shape by close adaptation to each 

 other. 



* Muller's Archiv. 1844. 



