'224: PROCEEDINGS OF THE 



for long periods of no rain and great heat, when fires are frequent, 

 which will greatly impair the chances of re-sowing from seed. 

 Hence, annuals will be at a disadvantage in such situations, and 

 biennials and perennials will be much more favourably placed. 

 Hence we find that the annuals are few, or, as Schweinfurth 

 observes, plants strive to become perennial. It is a well-known 

 fact that many plants which are in our climate annuals, become 

 biennial or perennial in the tropics, and vice versa. Those having 

 hypocarpogeal or underground fruits will also be at an advantage 

 in the case of fire, for their seeds and seed-vessels would not be 

 exposed to the flames. Hence, too, the necessity of each plant 

 being able to continue its existence by vegetative reproduction 

 from a tuber or bulb instead of from seed ! 



This brings us to consider shortly the function of these 

 structures in relation to growth. This is different in different 

 cases. In biennials with tap-roots, the root serves as a depot of 

 nutriment, which is to be utilized in the second year during the 

 flowering of the plant — i.e., is ultimately destined to be trans- 

 formed into seed. In the case of the Potato, on the other hand, 

 from the eye of each tuber a new plant proceeds, which is 

 nourished on the starch of the tubers, until, by its own leaves, 

 it is enabled to produce new tubers and flowers. Bulbs, again, 

 may be compared to resting buds, which in reality they are. 

 These are more characteristic of Monocotyledons, and, probably, 

 their nearest analogue is the cotyledons or albumen of the embryo, 

 bearing in mind that in the former case we deal with vegetative 

 repetition and in the latter with sexual reproduction. The amount 

 of water contained in these structures is remarkable. Thus, 

 Potatoes contain 75 or 76 per cent., Turnips, 91 per cent., Carrots, 

 86-i- per cent., Beet Hoot, 83|- per cent., &c, under cultivation. 

 These, of course, are unnatural, but they serve to indicate the 

 capacity of the plants in the way of storing up moisture for future 

 growth, and, consequently, of withstanding drought, which appears 

 to be the office fulfilled by them to the plants provided with tubers, 

 bulbs, or tap-roots. 



III. — On the Use of Coloration and Markings of Caterpillars, and 

 on the Development of the Insect. By Mr. Peter Cameron. 



Mr. Peter Cameron in his paper gave an account of some 

 observations he had made on the use of coloration and markings 



