1899] MORPHOLOGY OF THE STING IN HYMENOPTERA 245 



that the latter are not developed until the larval stage is reached, and 

 are therefore in no wise comparable to the abdominal appendages 

 which appear and disappear during the strictly embryonic period. In 

 fact, he confirms the conclusion of Heymons that the leg -rudiments 

 and the gonapophysal rudiments are in their nature quite distinct. 



Factors in the Growth of Muscle. 



We have previously noticed Mr. Alexander Meek's interesting conclu- 

 sion that in the post- embryonic history of striped muscles in various 

 mammals (cat, sheep, field vole, white rat) there is a reduction in the 

 number of fibres accompanied by a considerable hypertrophy of the 

 survivors. Dr. B. Morpurgo got a different result in examining the 

 white rat, and Mr. Meek briefly answered him, maintaining his position 

 that there really is in the history of a muscle " a struggle of parts 

 within the organism," and a resulting " survival of the fittest." 



In a more recent paper (Journal of Anatomy and Physiology, 

 xxxiii. 1899, pp. 596-608) he discusses the question in greater detail, 

 and as the subject is one of much practical and theoretical interest, we 

 quote his summing-up. " The life-history of muscle seems to be 

 determined by (1) inherited qualities, present in the fertilised ovum, 

 the evolution of which is controlled by (2) internal influences — internal 

 secretion (including the effects of 'sex'), the mutual influence of the 

 muscles upon one another, and of the fibres upon one another, and 

 the internal variations amongst the fibres ; and by (3) external 

 circumstances — work, food, habit, and indeed, the ordinary and 

 extraordinary conditions of extra-uterine life." 



" Up to the time of birth, in at any rate the higher mammals, 

 perhaps in all the Eutheria, hyperplasia characterises the growth of 

 muscle ; while after or about birth, hyperplasia ceases, and extra- 

 uterine life brings about a selection of some of the fibres at the expense 

 of their neighbours. In other words, during extra-uterine life, muscle, 

 according to its position, suffers more or less a reduction in the number 

 of its fibres, the degree of which is expressive of its functional import- 

 ance. The surviving elements are at the same time greatly hyper- 

 trophied, and the extent to which this takes place is also expressive of 

 the work which the muscle performs, or of which it is capable." 



Water- Plants as Land -Winners. 



In The Naturalist for August Mr. Albert Henry Pawson makes a 

 brief contribution to the study of the influence of water-plants on the 



