364 MR T. ARTHUR HELME ON HISTOLOGICAL OBSERVATIONS ON 



then is insufficient to prove the existence of fat granules in the muscle cells. We require 

 to have the tissues fixed, and also the assistance of osmic acid. 



Kilian assumes that, during pregnancy, new muscle cells are developed on the solitary 

 basis, that he found fibres of varying size ; but during pregnancy the connective tissue 

 is so greatly developed, that its cells are apt to be taken for young muscle cells. The 

 nuclear movements known as karyokinesis were unknown in his day. 



With regard to the theory of involution, which he caricatures, it seems at first sight 

 to resemble the description of the process which I shall have to offer, but I must point 

 out that this theory, out of which Kilian derives so much amusement, is a purely 

 mechanical one, the fibres being compared to sponges, as it were, which suck up the 

 juices during pregnancy, afterwards squeezing them out again. This looks like a 

 veritable " man of straw " specially built by Kilian for the purpose of having something 

 to destroy. He bases this theory of his on " the most superficial investigation ; " the 

 description I shall later give is, on the contrary, based on very careful and even prolonged 

 investigation, not on the examination of two uteri, but of a dozen or more. 



A second research has been lately carried out by Bernstein, who embodied his 

 results in his inaugural dissertation at Dorpat. This thesis I have not seen, being able 

 only to find a short reference in Schmidt's Jahrbuch for 1886, and certain quotations in 

 the papers of Sanger and Mayor. 



Bernstein investigated the puerperal involution of the uterus in rabbits, by making 

 measurements of the uterine connective tissue. He comes to the conclusion that the 

 connective tissue in the puerperium is absolutely diminished, but that it atrophies to 

 a slighter extent than the musculature, and that a not unimportant number of con- 

 nective tissue cells do not undergo fatty degeneration.* 



PART II. 



So much for the literature of the changes in the uterus. I shall now pass on to the 

 second part of this paper, namely, my own observations on the rabbit's uterus, taking 

 up — T. Pregnancy, II. Puerperium. 



Pregnancy. 



Here we consider the changes in the muscular and connective tissues and in the 

 blood-vessels. 



1. Muscular Tissue. 



Following closely as a corollary to Virchow's dictum " Omnis cellula e cellula," it 

 is believed that the cells of any one tissue are developed only from pre-existing cells 

 of the same tissue — that is to say, cells have an isogenous as contradistinguished from an 

 allogenous origin. With regard to non-striped muscle in particular, that this is the case 

 has been beautifully shown by the observations of Stilling and Pfitzner of Strassburg. 



* Schmidt's Jahrbuch, 1886. 



