PROGRESS OF MICROSCOPICAL SCIENCE. 143 



changed the intestinal surface, but every section wliicli I liave examined 

 from the specimen of intestine now under consideration, presents j)re- 

 cisely the same appearances. Peyer's gdands do not seem to he much 

 altered, quite to my surin-ise. Possibly they are slightly swollen, but 

 not otherwise perceptibly altered. But, after all, this is not so sur- 

 prising ; the storm is too brief to aifcct tissues beneath the surface to 

 any great extent. It is rather like a terrible tornado desolating 

 everything within its reach, but limited in its ravages to objects pre- 

 senting salient points of attack. The submucous connective tissue 

 and the muscular layer are both beautifully displayed, but neither 

 present any evidence of disease, imless the unusual sej)aration of the 

 mucous and muscular layers bo regarded as such." 



Unicellular Algce Parasitic within Fossil Corals. — A capital paper on 

 this subject was recently presented to the Geological Society of London, 

 by Professor Martin Dimcan, F.R.S., of which the following abstract 

 has been given. After noticing the works of Quekett, Rose, Wedl, and 

 Kulliker, which refer to the existence of minute parasitic borings in 

 recent corals, recent shells, and a few fossil moUusca, the author de- 

 scribes the appearance presented by a great system of branching canals 

 of about 0"003 millim. in diameter, in a Thamnastrfean from the Lower 

 Cainozoic of Tasmania. He then proceeds to examine the correspond- 

 ing tubes in Gonioplujllmn pyramidale from the Upper Silurian forma- 

 tion. In sections of that coral one set of tubes runs far into the hard 

 structure ; these are straight, cylindrical, and contain the remains of 

 vegetable matter. Neither these tubes, nor any others of the same 

 parasite, have a proper wall : they are simply excavations, the filiform 

 alga replacing the organic and calcareous matter abstracted. In some 

 places the dark carbonaceous matter is absent, and the lumen of the 

 tube is distinguishable by the ready passage of transmitted light. 

 Other tubes run parallel to the wall, and enter by openings not larger 

 than their common calibre. But there are others which have a 

 larger diameter, and in which the cytioplasm appears to have collected 

 in masses resembling conidia ; and where fossilization has destroyed 

 much of the continuity of a tube a series of dark and more or less 

 spherical bodies may be seen. In some places, especially in the spaces 

 between the minute curved dissej)iments and tabulfe, hosts of globular 

 spores, with or without tubes emanating from them, may be seen. 

 In Calceola sandalina corres2)onding structures exist sometimes, and 

 the method of entry of the parasite can be examined. The author 

 gave two instances, one of which was seen in section. A decided 

 flask-shaped cavity existed in the wall of the shell, opening outwards 

 and rounded and closed inwards. It was crowded with globular sjiores 

 (oospores), and these, where near the sides, had penetrated tlie hard 

 shell, and thus gave a rugged and hairy ajjpearance to the outline 

 of the flask-shaped cavity. After noticing minute structures in a 

 brachiopod included in a Silurian coral, and in a Lower Silurian 

 foraminifer, the author asserted, from the results of his late researches 

 upon the alga) parasitic in corals out of his own aquarium, that the 

 fossil and recent forms are analogous in shape, size, and distribution. 

 He considers that the old parasite resembles Saprolegnia fero.v in its 



