Francis E. Lloyd —152— Carnivorous Plants 



cretion, digestion and absorption (1897-9). Much later Kruck (1931) 

 did the same for the gland cells within the traps of Utricularia (to be 

 mentioned elsewhere). 



QuiNTANiLHA (1926) (on DrosopJiyllum), Dufrenoy and Homes ex- 

 amined the cells as a whole with reference to the comportment of the 

 vacuome. Homes has carried on most meticulous studies. He set 

 himself the task of determining first of all what happens during the 

 development of the cell during the ontogeny of the leaf and gland. 

 The next step was to determine if it is possible to describe definitely 

 the conditions of the glandular cells during repose, so far as this con- 

 dition might be reaHzed. To this end he depended not on plants col- 

 lected in the field, but on those raised under control, and which there- 

 fore, though secreting, were known not to have been stimulated by 

 insects, etc., but only by light, humidity, temperature. He then 

 studied glands during " digestion", that is glands which were actively 

 secreting enzymes and absorbing. 



The development of the vacuome during the ontogeny of the vari- 

 ous tissues, including the glands, follows a general course beginning 

 with minute droplets of material in solution (primordia or metachro- 

 mata). These enlarge, remaining spherical or more or less elongating, 

 and then give rise to rods or fine filaments which are straight or curved, 

 simple or branched, giving rise to thicker, short, large and massive 

 rods, turning gradually into vacuoles of very irregular shape. From 

 these by confluence arises a single massive vacuole with concentrated 

 contents from which may arise a vacuome with a fine, becoming a 

 coarser, even large and massive network from which in turn a defini- 

 tive single vacuole with " diluted contents" arises. Homes then re- 

 marks that these observed stages are not strictly common to all tissues, 

 e.g., parenchyma cells do not pass through a network stage, which 

 stage in any event is very transitory, and marks tissues or cells which 

 are very active, or are at a moment of particular cell activity. There 

 are, he continues, the following two essential phases: growth by the 

 augmentation of vacuolar substance, followed by growth by simple hy- 

 dration. All tissues commence with a vacuome in the form of meta- 

 chromata, and finish (certain tissues, including the glands, apart) with a 

 single vacuole with dilute contents. The more, however, a region 

 preserves the capability of specialization, the slower the evolution of 

 the vacuole. The glands, therefore, remain in a relatively juvenile 

 condition, and consequently more capable of immediate activity. 



In his second paper Homes followed the behavior of glandular cells 

 in order to find out what happens in them during the secretion of mu- 

 cilage only, so as to be able to distinguish later between this activity 

 and that which takes place during digestion and absorption. 



He found first of all that under natural conditions the gland cells 

 presented no uniform structural condition. But since in nature, that 

 is in plants studied in situ, it is impossible to know the precise history 

 of a given leaf, since it may have been digesting and recovered. Homes 

 raised plants from winter buds under control, regulating within ap- 

 preciable hmits the amount of illumination and humidity. Much to 

 his surprise, the glands of such plants were as Httle uniform in cytolog- 

 ical features as those in situ. That is, instead of finding a uniform 



