DEVELOPMENT OF FISH EMBRYOS -! ( .7 



a circulation of the- Idood iu the vessels. In spite of this 

 fact, <i complete circulatory system ira* developed irhich <li<l 

 i/of d/Jj'cr marked!;!, in rei/ard l<> flic direction ami flic 

 hranchintf of flic /vs.sv/.s /// flic cml>r//o and in flic i/olk-xac, 

 from find of a Wiindulus embryo dcrcloped in minimi xca- 

 trafcr. Heaps of red-blood corpuscles were found in the large 

 blood-vessels, such as the arteries of the yolk at the point 

 where they leave the embryo. 



The important result of these observations is therefore 

 the fact that a. complete rascular system, which is probably 

 identical in its main distribution and in its two vascular 

 divisions with that found in the normal embryo, can be 

 formed tritliont a. circulation, and therefore, iri/hoiit blood - 

 prexxiirc. A difference between the two, which also deter- 

 mines the limit of the possible identity of the vascular sys- 

 tems in the normal and abnormal embryos, is found in this, 

 that the luniina of the vessels in the poisoned embryo are 

 exceedingly irregular. The lumen of a vessel is in extreme 

 cases rosary-like, narrow and wide spots alternating with 

 each other. This is due to the absence of a sufficient intra- 

 vascular pressure. 



3. It might have been possible that a circulation lasting 

 only a short time had been present which I did not dis- 

 cover. I therefore made experiments with much stronger 

 KC1 solutions such iu which not even a trace of cardiac 

 activity ever appeared. In extreme cases I addded 5 g. of 

 KC1 to 100 c.c. of sea-water. I had previously ascertained 

 that a four-day-old embryo which had developed in normal 

 sea-water dies in two minutes in a ;$ per cent. KC1 solution. 

 XcrcrlhclcxH, tin- fcrtil'r.cd <'</</* developed normall// in a 5 

 per cent. KCl solution. They developed for three to six 

 lavs, and formed- what is of interest to us here a heart 



/ 



and a typical vascular system in the embryo and yolk-sac. 

 On the other hand, the development of the embryo as a 



