430 GERMINAL ORGANIZATION INDUCTION PHENOMENA 4 



genie effect, suppressed by methanol); by Toivonen (1945), ethanol-treated 

 heart muscle of fishes (lenses); by Toivonen and Kuusi (1951), ethanol-treated 

 ox liver or kidney (both together acrogenic and notogenic) ; by Okada (1948) 

 boiled frog ventral skin, which induces neural structures, perhaps acrencephalic ; 

 by Vahs ( 1 955) , mouse kidney boiled 1 5 minutes (only balancers) ; by Kuusi ( 1 953) , 

 pigeon muscles treated with ethanol (acrogenic); by Kriegel (1956), ethanol- 

 treated germinal vesicles (acrogenic); by Vainio (1958), a coagulum of entire 

 blood {homo, cavia) or of its various parts, which contain together notogenic and 

 acrogenic factors, thus present in our circulation. 



Let us add that Holtfreter (1955b) obtained some slight induction with dead 

 or dying pieces of mouse liver or kidney which were coated with agar, in conditions 

 which excluded intimate contact between graft and reactor. 



Forelimb rudimencs 



Fin 



Notochord 



Myotomes 



Pronephros 



Mesenchyme 



Proctodaeum 



Neural cells? 



° 5 10 15 



No. of specimens 



Fig. 84. A histogram of the inductions obtained with ethanol-treated bone marrow of 

 guinea pig. Implantation in the blastocoele of newt gastrulae. From Toivonen, 1953. 



A special interest is attached to the guinea pig bone marrow (from the thigh) 

 which Toivonen (1953, 1954a, b) used after 24 h. in ethanol and described as a 

 purely (or nearly pure) mesodermal inductor (Fig. 84). If first boiled and then 

 treated with ethanol, the same tissue, implanted in the blastocoele, induces 

 lenses and lialancers while, when explanted in sandwiches, its action is limited 

 to lenses or lentoids, with neither balancers (or at the most very poor ones) nor 

 neural crest derivatives. This is a new instance of a shifting by heat in the acren- 

 cephalic direction. Toivonen and Saxen (1955a) then proceeded to combine the 

 inducing effects of the two tissues of the guinea pig which, when submitted to 

 ethanol, exert "complementary" induction, i.e. liver and bone marrow, acrogenic 

 and notogenic respectively. In this case, the effect of liver tissue has been re- 

 examined with the appreciable rectification that, especially if originating from 

 well-fed animals, it does not only induce an acrencephalon and its related sense 

 organs, but also a chordencephalon with or without its otocyst(s). The possibility 

 of obtaining combined fore- and hind-brain inductions, without any trunk 

 component, appears already in the results (see infra) of Kuusi (1951). Bone- 

 marrow on the other hand is not completely notogenic, because a neural tube is 

 practically lacking. The two tissues, previously fixed in 70% ethanol, were im- 

 planted together either in the blastocoele or in an ectoblast sandwich. In both 

 cases, the characteristic effect appeared centred on the individual inductor, but 

 with distinctly more trunk or tail spinal cord than could be obtained in the 

 controls with each inductor separately (Fig. 85). Thus, "the spinal cord can only 

 be induced when the inductors contain agents capable of inducing both hind- 



