818 REPORT— 1893. 



9. Cn Idme Salts in relation to some Physiological Processes in the Plant. 



By Dr. J. Clakk. 



The seeds of many Alpine and other plants when germinating at a low tempe- 

 rature are incapable of utilising their reserve food-supplies to any great extent, 

 unless there be 1 to 15 per cent, of carbonate of lime present in the soil, the 

 quantity varying with different species. When germination takes place at a low 

 temperature, say 5° C, on a soil where the carbonate of lime falls below the 

 necessary minimum, the seedlings perish. When seeds of the same species 

 germinate at a temperature varying from 15° 0. to 30° C. in a soil poor in lime, 

 nearly the whole of the reserve food-supply is utilised, and if subsequently removed 

 to a more congenial temperature, the seedlings continue to grow in a normal 

 manner. Either lime or a high temperature is therefore necessary for the trans- 

 location of material from the seed to the growing parts of the seedling. The 

 varyiiig amount of carbonate of lime present in the soil must consequently be a 

 powerful factor in determining the local distribution of plants. 



In connection with the occurrence and distribution of lime salts in the living 

 plant, the author has been led to the conclusion that the disappearance in the 

 spring of the calcium oxalate accumulated in the bark of many trees during the 

 previous autumn is probably due to the activity of certain bacteria. These bacteria 

 are capable under favourable conditions of converting calcium oxalate into calcium 

 carbonate, and are found in the early spring associated with the cells in which the 

 oxalate is stored. 



10. On the development of the ' Ovipositor ' in the Cockroach (Periplaueta 

 orientaiis). By Professor A. Denny. 



It is well known that in the adult female of this familiar insect the abdomen 

 is possessed of only seven sterna, while in the male we find nine well developed. 

 That the two missing sterna in the female are represented by the ' ovipositor ' has 

 long been known, but up to the present time their development does not appear to 

 have been completely worked out. An examination of a complete series of prepara- 

 tions has brought to light several new facts which necessitate a revision of the 

 usually accepted views concerning the morphology of this organ. In the first 

 stage (recently hatched) the abdomen presents nine sterna similarly developed in 

 both sexes, and in each case the terminal sternum is characterised by a pair of 

 unjointed ' styles ' (a ieature peculiar to the male in the adult). The ninth sternum 

 at this stage shows a posterior median cleft, which in subsequent stages deepens 

 and widens until the body of the sternum is almost divided into separate halves. 

 In an early stage of development tvro pairs of simple unjointed appendages (the 

 gouapophyses) appear in connection with the eighth and ninth sterna. The ap- 

 pendages of the ninth sternum at first lie upon its dorsal surface and are not visible 

 from the exterior, but are afterwards brought into view by tlie division of the 

 sternum. The separated halves of the ninth sternum by degrees assume an appen- 

 dage-like outline, and eventually become the so-called outer pair of 'posterior 

 gouapophyses.' Thus, in the ovipositor of the adult the three pairs of appendages 

 are not homologous (as generally supposed), there being a pair of anterior gona- 

 pophyses and a pair of posterior (inner) gouapophyses which originate as appen- 

 dages of the eighth and ninth sterna respectively, while the so-called 'outer' posterior 

 gouapophyses have a diiferent origin, being formed by metamorpliosis of the ninth 

 sternum. The eighth sternum gradually diminishes in size up to the final stage, 

 where it is represented by little more than the small median plate which supports 

 the spermatheca (which has hitherto been regarded as representing the ninth 

 sternum), and a pair of plates upon which rest the anterior gouapophyses, 

 generally described as basal joints of these appendages. Further, the thin plate 

 which carries the aperture of the uterus is not the eighth sternum (as usually 

 supposed), but originates as a fold of the intersternal membrane between segments 

 seven and eight. 



