192 SUMMARY OF CUKKENT RESEARCHES RELATING TO 



Gobsea scandens var. alba indicates that in the formation of the micro- 

 spore no cell-plate is apparent during the division of the cytoplasm. 

 There is a general similarity to the process observed in Nicoiinna, and 

 the '.' hyaline areas " which accompany the cleavage of the cytoplasm 

 strongly resemble those seen during spore-formation in the fungi Pilo- 

 bolus and FuUgo . It is significant that similar cytoplasmic differentiation 

 occurs under similar conditions in such widely separated forms. In all 

 cases observed these " hyaline areas " are formed during cytoplasmic 

 division of a multinucleate cell in which cell-plates are not formed, and 

 they bound off a single nucleus and never a group of nuclei ; they may 

 also indicate a future cleavage in a uninucleate mass. It is probable 

 that the nuclei may control the orientation of the " hyaline area " or 

 fuiTows, and that the latter constitute visible expressions of the activity 

 of the nuclei. It has been suggested that soluble ions are diffused along 

 the paths of the fibres, and if this is so, the compounds formed by the 

 ions would be most concentrated around the fibres in the equatorial 

 planes, so that it is possible " that in these regions of highest concentra- 

 tion the substances may be in the necessary condition for the development 

 of the plasma-membrane, and that in this manner tliev determine the 

 position and direction of the penetrating furrows." ' S. G. 



structure and Development. 



Vegetative. 



Anatomy and "Biology of Lathrgea.— E. Chemix {Ann. Sc. i\al, 

 1920, 10, No. 2, 125-27] , 88 figs.). The writer has studied the germina- 

 tion of the seed, and the development of the root, suckers, scales and 

 glands, of L. dandestina, and has compared his observations with those 

 of other writers upon L. squamaria. In both species the root-system is 

 mainly adventitious, but while in L. dandestina the roots are orange- 

 yellow with a thick lacunar cortex, which serves as storage-tissue, iw L. 

 squamaria the roots are whitish in colour, and have a thin cortex con- 

 taining very httle food-material, exfoliation being frequent. In the 

 former species the endodermis has lignified thickenings and functions as 

 an internal layer of the cortical tissues ; in the latter the cell-walls of 

 the endodermis are suberised, and the numerous cells retain their iudi- 

 viduaHty. The suckers are lateral swellings of the root— relatively 

 large and yellowish in colour in L. dandestina, smaller and whiter in L. 

 squamaria. They usually penetrate as far as the wood of the host ; in 

 L. dandestina they attach themselves to the conducting vessels, but in 

 L. squamaria they attain their greatest development in the phloem- 

 parenchyma. Hydrocarbons and nitrogenous compounds are obtained 

 by breaking down and digesting the adjacent tissues of the host ; starch 

 and allied carbohydrates by the solution and absorption of these sub- 

 stances. Usually the host forms a layer of growth which serves the 

 double purpose of isolation and renewal of the affected area ; no 

 permanent injury is caused to the main root-system, except when a 

 weakly plant is attacked. The scales of Lathrsea are not atrophied 

 organs, neither do they play any part in the nutrition of the plant ; they 

 are modified leaves which act as excretory organs, giving off excess of 



