348 BOTANICAL GAZETTE [may 



then washing away the chloral hydrate in water and growing the tips in sawdust, 

 Nemec found that after 20 hours many cells have become binucleate. After 27 

 hours few cells are binucleate, but many contain large nuclei which contain 28 

 chromosomes, twice the 2X number. After 40 hours the mitoses show regularly 

 14 chromosomes, the 2X number. Nemec believed the quadruple number to be 

 brought back automatically to the 2X number by a heterotypic mitosis. 



Strasbukger^^ has traversed the same ground, treating material of P/^^oh 

 sativum in the same way and making an exhaustive study of all the cytological 

 phenomena. He found cells with two nuclei and observed that such nuclei fuse 

 to form large nuclei with 28 chromosomes, the quadruple number; but such 

 mitoses, aside from the large number of chromosomes, present no striking peculi- 

 arities. There are abnormalities, due to the chloralization, but there are no char- 

 acteristics of the heterotypic mitosis or anything else to indicate a reduction to the 

 2x numberj but rather there is evidence that the 4.T number, once established, 

 persists. 



The investigation of chloralized nuclei was made particularly exhaustive, that 

 it might form a basis for comparison with nuclear phenomena in graft hybrids. 

 An investigation of typical and chloralized nuclei of Laburnum vidgare, Cytisus 



pu 



autoregulat 



ihese plants gave no response to such chloralizing as that described lor risum 

 sativum, and after greater stimulation nuclear divisions were not resumed. The 

 study of nuclear phenomena threw no Hght upon the problem of graft hybrids. 

 There were no heterotypic mitoses and the author doubts whether heterotypic 

 mitoses are to be found in vegetative or somatic tissues. Such mitoses as those 

 described by English writers for malignant tumors Strasburger believes to be 

 incorrectly interpreted. 



The noted Mespilus at Bronvaux, recently studied by Noll, is discussed, and 

 here again there is no evidence of fusion or reduction. A study of the Bizzana 

 orange compared with "Agrumi," which is not a hybrid, showed no cytological 

 differences; both have 16 chromosomes. The evidence showed that Bizzaria is 

 a hybrid of sexual origin and that there is nothing to support any theorj' of auto- 

 regulation. 



The paper gives a full account of the cytological details of graft hybrids, 

 together with theoretical discussions which cannot be treated adequately in a 

 brief review. — Ch.4rles J. Chamberlain. 



Phototropism and perception of light.— Fitting has undertaken^' to solve 

 the question whether a localized tropic or nastic sensitiveness must be considered 

 as a sign of lo calization of the perceptive faculty for the stimulus, and whether it 



" Str.\sbtjrger, Eduard, Ueber die Individualitat der Chromosomen und die 

 Pfropfhybridcn-Frage. Jahrb. Wiss. Bot. 44:482-555. ph. 5-7. 1907- 



Fitting, H., Lichtperception und phototropische Empfindlichkeit. Jahrb. 

 Wiss. Bot. 45:83-136. 1907. 



12 



