320 NATURAL SCIENCE. %^- 



TO CORRESPONDENTS. 



A II communications for the Editor to be addressed to the Editorial 

 Offices, 67-69 Chancery Lane, London, W.C. 



Reproduction of the Foraminifera — (J. Eliot Jenkinson, Edinburgh). — No 

 very definite information has as yet been obtained on this subject, but important 

 details have been accumulating since 1854, when Max Schultze, in his "Organismus 

 der Polythalamien," figured a Miliola and a Rotalia, in both of which numerous 

 young shells are shown. Among the Foraminifera it is likely that both fission and 

 gemmation obtain, and there is evidence of viviparous reproduction following 

 segmentation. Strethill Wright has noticed the young in Spirillina [Ann. Mag. Nat. 

 Hist. [3], vii., 1861, p. 360); Carpenter treated exhaustively of the subject up to his 

 time in his " Introduction," 1862 ; and Schacko (Arch iv. Natiirg . xlix., 1883, p. 428. 

 and Sitz. Ges. Nat. Frexinde Berlin, 18S2, p. 130) has figured and described Peneropiis 

 proteus showing the last fourteen chambers of the shell crowded with embryos, while, 

 to be more exact, he figures another specimen, to prove that the shape of the embryo 

 corresponds precisely with the original chamber of the parent shell. In 1884, Brady 

 ("Challenger " Report) figured a specimen of Cristellana crepidula in which young shells 

 are seen to occupy some of the chambers; and in a more recent paper " On the 

 Reproductive Condition of Orbitolites complanata, var. laciniata " [Journ. R. Micros, 

 Sac, 1888, p. 693), this condition is beautifully shown. Carpenter had already 

 noticed this in 1862, and Semper, in 1863, had been very near to Brady's discovery 

 [Zeitschr. Wiss. Zool., xiii., 1863, p. 558). (See also Schlumberger, Bull. Soc. Zool. 

 France, xiii., 1889, p. 222.) As there is no orifice in the three genera last mentioned 

 sufficiently large to allow of the passage of the young to the exterior, it seems highly 

 probable that the birth of the young means the destruction of the parent, unless 

 (which appears to be the case) an actual segmentation of the parent takes place to 

 produce the young. We see the same thing when Amoeba divides into two; the 

 parent ends independent life and becomes two immature individuals. In Cymbalopora, 

 the last or youngest chamber of the mature shell is much inflated, and young shells 

 are found therein ; and Brady noticed the presence of the rotaline portion of the 

 mature shell, showing traces of the fractured balloon-shaped chamber in a gathering 

 of mature and young individuals (" Challenger " Report). It is possible, therefore, 

 that in Cymbalopora also, the birth of the young means the destruction of the parent. 

 The most recent figure bearing on the subject is that of a Lagena, containing a young 

 shell, which is given in a paper by Chaster in the Anit. Rep. Southport Nat. Hist. Soc, 

 referred to on p. 159 of our issue for April. 



With regard to the question of sex, De la Harpe, when studying the Nummu- 

 lites [Mem. Soc. Pal. Suisse, vii., 1881, p. 127; Bull. Soc. Geol. France [3],ix., 1881, 

 p. 171), observed that there are two recognisable forms of each species, the 

 individuals being divisible by size ; and, further, that the smaller shells invariably 

 begin with a large chamber, while the larger shells either have no recognisable 

 central chamber, or one of very small size. Parker and Jones had previously noted 

 the same thing. De la Harpe considered these variations as specific. Munier- 

 Chalmas and Schlumberger took up the question, and came to the conclusion that 

 the difference was one of development only, and that the " pairs " were two 

 forms of the same species [Bull. Soc. Geol. France [3], viii., 1880, p. 300; ibid., x., 

 1882, p. 470; ibid., xiii., 188s, p. 273; Comptes Rendus, xcvi., 1883). Schlumberger 

 has found this dimorphism in all the Milioline Group, and all his recent papers (in 

 the publications of the Geological and Zoological Society of France) may be con- 

 sulted on the subject. De la Harpe, in one of the papers quoted above, suggests 

 that, had it been a fact that sex existed among the Foraminifera, he would have 

 been inclined to regard the size of the central chamber as of a sexual nature, and 

 Patrick Geddes seems to agree with this suggestion [Proc. Roy. Soc. Edinb., 1885-6 

 [1886], p. 931). The subject has been referred to in many other papers; it is 

 impossible to give a complete list here, but they will all be found in Sherborn's 

 " Bibliography," published in 1888. 



