6 Transactions of the Society. 



thesis (6) having: for its principal object the identification (Verein- 

 igung) of Psammosphmra fusca as a " young or immature stage of 

 Saccammina sphsericay His researches are largely based upon 

 the occurrence, in a sessile form attached to the tests of Saccam- 

 mina spliderica, of an organism which he regarded, owing to its 

 position and the structure of its shell- wall, as the primordial stages 

 or chambers (Primativgehduse) of Saccammina. He concludes that 

 this organism originates in an amoeboid extrusion of protoplasm 

 from the Saccammina, which naturally settles down as a test-form- 

 ing organism either upon, or in the neighbourhood of, its parent- 

 shell. According to Dr. Ehumbler these Primativgehdicse are usually 

 attached to the surface-contour of Saccammina near to its orifice, 

 but he admits their occurrence attached to small stones and other 

 organisms. The figures which he publishes show, first of all, a 

 small sessile mass of very fine sand- grains mixed with, sponge- 

 spicules and diatoms, the whole organism being not much larger 

 than one of the largest sand-grains forming the shell of the parent 

 Saccammina. 



Later stages, according to Dr. Ehumbler, show an increase in the 

 number of sponge-spicules, which at a still later stage are discarded 

 and replaced by sand-grains and shell-fragments. Following these 

 stages of growth, Dr. Ehumbler asserts that the sessile organism 

 reduces its base of attachment to a single sand-grain surface, and 

 finally detaches itself from the parent Saccammina and commences 

 a free existence in a form which he considers to be identical with 

 the Psammosphmra fusca of Schulze. He accounts for the fact 

 that the child is now as large as, or larger than, its parent by pos- 

 tulating that the size is relatively one of external appearance only, 

 due to the large dimensions and projecting external angularities of 

 the constituent sand-grains. He figures as the next stage a Psammo- 

 s'p'hdera-\\]s.Q test with an irregular aperture level with, or sunk 

 beneath the contour-surface of the shell-wall, and from this form 

 of aperture he traces the gradual evolution of the nipple -shaped 

 protuberance {Pylomtnbus), which signalizes the completion of the 

 adult test of Saccammina. 



From the elaboration of these details and from an extensive 

 and highly technical investigation relative to the nature of the 

 shell-cement and its composition, and to the sarcode-body ( WeicJi- 

 korper) and its nuclei, Dr. Ehumbler considered the identity 

 ( Vereinigung), of the two forms to be established. Mr. J. J. Lister 

 (7, 8) accepts, with more or less reservation, the deductions of 

 Dr. Ehumbler, as also does Dr. F. Liicke (9) who repeated many 

 of his experiments and confirms his general conclusions, although 

 he failed to confirm by experiment much of the evidence tendered 

 by Dr. Ehumbler. It must also be borne in mind that Dr. Liicke's 

 work is a thesis leading to his Doctorate degree at Kiel University, 

 and is rather a review of Dr. Ehumbler's work, accompanied by a 



