818 EXPERIMENT STATION RECORD. [Vol.40 



sexual cells of the female plant, and especially through the cytoplasm. Cell 

 and nuclear divisions involve occasionally loss of material, as parts of chromo- 

 somes, this fact affecting the genotypic constitution of the cell. It is assumed 

 that occasional hybridization can give rise to apogamous or sexually abnormal 

 new species, which persist as minor species or biotypes. In case of Humulus 

 hipulus, which can develop fruits containing embryos on pollination with 

 various related plants, pollination with Vrtica urcns produced large and strong 

 fruits, though these were incapable of germination. It is presumed that a truly 

 heterogeneous fertilization took place, that the hybrid was capable of develop- 

 ment as long as it was nourished by the mother plant, but that lack of internal 

 homogeneity rendered it incapable of independent activity. 



The mitochondrial origin of plastids. A. GUTLIXEBMOND {Compt. Rend. Acad. 

 Sci. [Paris], 161 (1918), No. 12, pp. 430-J f S3).— This is mainly a discussion of 

 recent contributions of Mottier (E. S. R., 39, p. 332) and of Cowdry (E. S. R., 

 38, p. 524). It is considered as certain that the plastids in plants arc derived 

 by differentiation of mitochondria substantially Identical with those of animals. 



A colloidal hypothesis of protoplasmic permeability. E. E. Khke (Plant 

 World, 21 (1918), No. 6, pp. 141-150). — This hypothesis, which is to be discussed 

 in a later paper, [Deludes the assumption that the colloids are of the emulsion 

 type, consisting of 2 (or possibly more) liquid phases which may differ, as 

 regards composition, only in the relative proportions of the water ami sub- 

 stance of the colloid or the proportion may even be reversed. Thus a gelatin 

 sol is believed to consist of globules containing' relatively more gelatin, 

 suspended in a medium which contains relatively less gelatin. The medium 

 may be thought of as a more dilute gelatin solution, the globules as a more 

 concentrated one. At greater total concentrations of gelatin this condition 

 may be reversed on passage of water from one phase to another with marked 

 changes of properties, bo that anything that changes the distribution of water 

 between the phases will greatly affect the properties of the material. Tins dis- 

 tribution of water is known to be affected by temperature, the presence of salts 

 and other solutes, and even by mechanical stresses, all these affecting such 

 physical properties of the colloid as viscosity, sometimes in large degree. 



It is considered probable that similar conditions may occur in protoplasm, 

 that two at least of the liquid phases of protoplasm differ mainly as regards 

 relative water content, and that the distribution of water between those two 

 phases may be altered without causing the death of the protoplasm. This 

 hypothesis is discussed in regard to its supposed bearings. 



Colloidal phenomena in the protoplasm of pollen tubes: The effect of 

 potassium and sodium on hydration and growth, F. E. LLOTD [Carnegie Inst. 

 Washinaton Y<ar Book, 11 (1918), pp. 61. 6S). — In continuation of work pre- 

 viously noted (E. S. R., 40, p. 28), the author has given attention to the com- 

 parative effects of sodium and potassium In the form of hydrate. 



The hydration capacity of pollen of Phaseolus is Increased by both hydrates 

 (but more by potassium) over that of water with 20 to 25 per cent sugar solu- 

 tion employed alone. This increased hydration capacity expressed itself partly 

 in growth and partly In swelling in excess of growth. Potassium appears to be 

 absorbed more vigorously than is sodium by the protoplasm or by some element 

 in the colloidal complex which is now regarded as protoplasm. A toxic effect 

 also is more obvious in the case of potassium. The observations are supposed 

 to be significant in view of the physiological effects of the two metals. 



The colloidal properties of certain plant mucilages as affected by stains. 

 F. E. Lloyd (Carnegie Inst. Washington Year Book. 11 (1918), p. 12). — Having 

 observed that when substances such as the mucilaginous products of hydrolysis 

 of cellulose walls which occur during abscission, the ripening of fruit, etc., are 



