Intiuence of Corpus luteum Extnicts upon I'hiin MuHcle 5 



movements" of the intestine; and (2) alterations in the treneral condition 

 of contraction of the tissue, i.e. alterations in tone, these beinj; either in 

 the direction of increase of contraction or of diminution. Tlu- {^reater 

 number of my experiments were made upon the uterus of the rat, and 

 these may therefore be considered tirst. 



EXPEKIMENT.S IFON THK R.\t's UtEHUS. 



At the moment when the ordinary Locke-Ringer solution was replaced 

 by that containing extract of corpus luteum the immersed portion of 



Fig 2.-Tracing of cornu of rat's uterus sho^ving effect of immersion in extract of corpus luteum 

 of cow. The tracing shows increase of tone, with rhythmic movements the -^mphtude of 

 which gradually increases, the tonic contraction remaining at about the same level, i he time 

 markings in this and in all the succeeding figures are m one imnute. 



uterus showed in the majority of cases marked increase of tone, havmg 

 almost the appearance of tetanus. A typical instance of such a tracmg 

 is shown in fig. 2, in which it will be observed that the increase of tone 

 soon begins to show rhythmic contractions and relaxations, the amplitude 

 of which gradually increases, although the maximum tonic contraction 

 remains at very much the same point. On substituting normal Locke 

 solution the effect at once begins to pass off. , ,, • 



Variations were observed in the effect of the extract upon the rhythmic 

 contractions. Sometimes these remained at the same rate as in ordinary 

 Locke solution ; at other times they became more frequent. In some cases 

 the uterus was quiescent before the action of the extract Under these 

 circumstances extract of corpus luteum usually stimulated the uterus to 

 spontaneous contraction. This is shown in fig. 3. An effect of corpus 



