66 Transactions of the 



cells themselves, or are only called forth under certain circumstances, 

 and by external influences, has, as far as I could ascertain, not been 

 decided. Nevertheless, judging from the facts thus far observed, it 

 seems not to be imiDOssible that the amoeboid movements in the 

 colourless blood corpuscles should also occur in the circulating blood 

 under physiological conditions; for it would be difficult to prove 

 that these bodies were only endowed with this power of changing 

 their form for the sole purpose of escaping from the vessels during 

 the process of inflammation, either to serve subsequently for some 

 other formation process, or to be eventually thrown off by the 

 organism in the form of pus. 



According to my own observation it is principally the larger, 

 and therefore older colourless blood cor})uscles, which manifest the 

 most active movements. The nucleus, which becomes during these 

 movements alternately uncovered and enveloped again, remains, as it 

 appears, in a passive condition. In some cases, I observed it even 

 entirely uncovered, adhering only to the margin of the protoplasm in 

 motion, and actually dragged along by this for a little distance. 

 The nucleus is, as abeady mentioned, perfectly round, smooth, and 

 almost flat ; in some cases even already of a somewhat pale-yellowish 

 tint. It therefore already possesses, including the diameter, all the 

 characteristics of an embryonic colom'ed blood corpuscle, and corre- 

 sponds exactly to a portion of those bodies above described, which I 

 observed in the blood of human embryos. 



Looking upon these facts from a general point of view, it appears 

 more than probable that in the blood of man, at least, only the 

 nuclei of the colourless blood corpuscles are concerned in the 

 metamorphosis into coloured corpuscles. In the blood of amphibia, 

 this seems, as I shall hereafter demonstrate in another treatise, not 

 to be the case. 



As regards the amoeboid movements of the surrounding layer of 

 protoplasm, their cause may perhaps be attributed to the presence 

 of the nucleus itself, or, in other words, to that of the young 

 coloured corpuscle approaching maturity. In a similar manner, as 

 the matured ovum engenders the stimulus, calling forth those con- 

 tractions of the uterus necessary to its expulsion, so also may the 

 matured nucleus of the colourless blood corpuscle give rise to those 

 amoeboid movements of its enveloping layer of protoplasm, which 

 finally cause its liberation. After the nucleus is liberated in this 

 manner, the enveloping protoplasm undergoes a gradual disintegra- 

 tion. Such disintegrating masses of protoplasm are constantly met 

 with in the circulating blood ; sometimes a liberated nucleus still 

 rests upon them, while again it is entu*ely absent ; their extended 

 amoeboid form points to movements as having taken place prior to 

 their death. In the blood of a man poisoned by cyanide t)f 

 potassium, I observed, eight hours after death, a number of these 



