THE CESTROUS CYCLE IN THE MAMMALIA 63 



regarding the behaviour of the metabolism. Schroder, 1 who investi- 

 gated the nitrogen metabolism, found a retention of nitrogen 

 immediately before and during menstruation (cf. Potthast, etc., for 

 dogs, p. 49), but other investigators have obtained somewhat different 

 results. 2 Zimtz has shown from numerous experiments that, contrary 

 to the conclusions of other authors, there is no evidence of a 

 constant variation in the respiratory exchange during the menstrual 

 cycle. (For changes during pregnancy, see Chapter XI.) 



Mosher 3 states that there is a fall of blood pressure at the time 

 of menstruation. Zuntz 4 records a diminution in the pulse-rate. 



Sfameni 5 states that there is a decrease in the quantity of 

 h.t-inoglobin in the blood during menstruation. He says also that 

 the number of blood corpuscles increases in the days immediately 

 preceding the haemorrhage, but is diminished during it. 6 



liirnbaum and Osten 7 state that in the blood of menstruating 

 women coagulation is retarded. This statement is based on 

 experiments made by adding fibrinogen to menstrual blood-serum. 



Blair Bell 8 states that in connection with menstruation there is 

 a marked drop in the calcium content of the systemic blood, and 

 that this is most marked just before bleeding begins. This is 

 correlated with an excretion of calcium salts in the menstrual 

 discharge, an examination of which revealed the presence of a 

 considerable quantity of calcium, both free and within the leucocytes 

 (see p. 81). This excretion of calcium during menstruation is 

 regarded by Blair Bell as connected phylogenetically with the 

 process of egg-formation by birds and other lower Vertebrates. 



Further, this author is disposed to believe that the calcium 

 metabolism, under the direction of the ovaries and. other ductless 

 glands, is concerned in the phenomena of menstruation. He refers 

 especially to the following points: (1) Calcium salts are necessary 

 for the repair of all lesions. Therefore the presence of menstruation 

 is dependent upon a healthy condition of the organism, and its 

 claims on the calcium metabolism at any particular time (cf. absence 



1 Schroder, " Untersuchungen iiV>er den Stoflwechsel wiihrend der Men- 

 struation/' Z<> ittftt /./'. klin. M<><lif!n, vol. xxv., 1894. 



- See von Noorden, /or. fit. 



'' Mosher, "Blood-pressure during Menstruation," Jnhns ///<//'/'., /Ai.-t////.// 



ll<-t-u>, 1901. 



4 /mitx, (of. fit. 



'' Sfanicni, Iff. fit. 



u Cf. Carnot and Deflandre, ''Variations du nomluv <!- H.'iiiatics rh.-/ la 

 pendant la periode meiistnifllf." C. It. <!< '" >'" '/ /<'"</., vol. l\\i., 

 1909. 



7 Birnbaum and Osten, "Untersuchungen iil>er die Gerinnung dr> l'.lnti-> 

 wiihrend dor Menstruation," J /</>. /'. Oynax., vol. l.xxx., 19C6. 



8 Blair Bell, ' Menstruation and its KYlation to the Calcium M.-tal>..lism. v 

 Proc. Roy. 8oc. JAW., July 19<>s. Se.- also 1,,-low. p. 



