ETIOLOGY OF MALFORMATIONS 187 



attention, with pleiomerous, partly proliferous flowers has been proved to be 

 heritable \ 



In conclusion I may mention the research of Heinricher 2 , who found that 

 the second staminal whorl which is normally absent in Iris could be handed 

 down as a hereditary character. The members of this whorl are indeed very 

 variable; sometimes they appear as arrested stamens, sometimes as completely 

 formed ones ; they may be staminodia with or without pollen-sacs, or they are 

 style-like structures. A perfect fixation, that is to say, the breeding of a stock 

 with only atavistic flowers, has not yet been attained ; but it is of special interest 

 that flowers have appeared in which the inner perianth was constructed like the 

 outer, and that a flower-form has also been found which diverged far from the 

 ordinary one and may perhaps be considered as an advance in development of 

 the reverted type. 



B. There is another series of cases those in which malformations 

 have been experimentally evoked. Here we leave out of consideration 

 the phenomena as they are determined by want of light and like 

 agencies. 



The lower plants, especially the Fungi, are particularly favourable for 

 this kind of investigation, and a few examples may be cited : 



Dematium pullulans, which consists commonly of ordinary hyphae 

 or of yeast-like sprouts, if it be cultivated for a long time in a temperature 

 of 30-31 C. produces cell-masses by the division of its cells in every 

 direction of space, and the individual cells in these masses may at a 

 normal room-temperature again sprout out in a yeast-like manner 3 . The 

 interesting malformations which Raciborski has recently produced in 

 Basidiobolus ranarum are in a certain degree analogous 4 . This plant 

 normally consists of uninucleate cylindric cells arranged in a thread-like 

 series, and it is easily cultivated in a nutritive solution. If the concen- 

 tration of the solution be gradually increased the cells always become 

 shorter and approach the spherical form and their dividing walls become 

 more oblique ; this never happens in normal growth. If now the culture 

 is brought into a io/ glycerine solution at a higher temperature, say 

 30 C., plurinucleate giant-cells with a diameter of 60 ^ frequently develop 

 and between some of the nuclei delicate cell-walls appear. All the cells 

 do not react alike. It is evident that here a profound disturbance of 

 the growth has taken place; the giant-cells have no power of develop- 

 ment ; they die off. Other abnormalities need not here be mentioned, 



1 Magnus, Teratologische Mitteilungen, in Verb. d. hot. Vereins. d. Provinz. Brandenburg, 1882. 



2 Heinricher, Versuche iiber die Vererbung der Ruckschlagserscheinungen der Pflanzen, in Pringsh. 

 Jahrb. xxiv. 



3 Schostakowitsch, Uber die Bedingungen der Konidienbildung bei Russthaupilzen, in Flora, Ixxxi 

 (Erg.-Bd. z. Jahrg. 1895), p. 376. 



4 Raciborski, Uber den Einfluss ausserer Bedingungen auf die Wachstumsweise des Basidiobolus 

 ranarum, in Flora, Ixxxii (1896), p. 107. 



