DENDROSOMA RADIANS. 



Stein, with whom this strange theoiy originated, long ago gave it up. 

 It is even suggested that Dendrosoma may be an Actinophrys, or an 

 Anthophysa. 



The name Dendrosoma, from the Greek S^vSpov a tree, and aw/j-a 

 a body, fairly expresses the idea generally entertained as to the character 

 of this creature, (Plate II., Fig. 1,) each of the tentaculated prominences 

 being set down as an animalcule joined to a common stalk or pedicle, 

 the whole forming, as Perty described it, an aggregated Actinophrys, in 

 which individuals are collected into a colony ; reproduction was 

 supposed to take place by gemmation, a process familiar to us in the 

 common Hydra. This recalls to my mind a well-worn illustration, for 

 which, it is said, we are indebted to Buffon. He pointed out to the 

 lexicographers that their description of a crab as " a httle red fish which 

 rvins backwards," was wrong in just three particulars, namely, that it was 

 not a fish, that its coloiar was not red, and that it did not run backwards. I 

 think that a similarly radical criticism might be applied to the usual des- 

 cription of Dendrosoma, for, in the first place, it is one individual, and not 

 a colony ; in the second, it is an Acineta, and not an Actinophrys ; and, iu 

 the third, the process of budding does not appear to be one of its modes 

 of reproduction. 



Its size, which varies considerably, is stated in the Micrographic 

 Dictionary as l-y6th of an inch in length, but this is much under the 

 mark, as I have measured specimens as long as 1-loth of an inch, or 

 more than six times the published measurement. Seen in the 

 microscope, with a fairly high power, it has a tree-like stem, generally 

 covered with foreign matter, which adheres to its viscous surface, and, 

 for this reason, it is difficult to see through the object with sufficient 

 clearness to make out its structure. The whole of the pedicle, when 

 rendered perfectly clean, is highly transparent, and is seen to be full of 

 granules and contractile vesicles, the former differing greatly in size, 

 and the latter so numerous that, in a staiwed specimen I had under 

 observation, they might have been fitly compared to marbles iu a bag. 

 These granules, which are neither more nor less than particles of food 

 after ingestion, are seen to be in active circulation. The currents appear 

 to be four, two upwards and two downwards, but of course are really 

 only half that number, as they make a double circuit of the whole 

 creature ; reminding one of the motion of the sap in Chara or Nitella, 

 only that in each cell of those plants there is one continuous stream 

 instead of two. 



At irregular intervals, not alternate as generally stated, the stem 

 branches out into somewhat rounded bud-hke heads, the form of which 

 the creature is able to modify greatly. From these it extends a variable 

 number of extremely fine tentacles, each of which has a httle knob at 

 the end, or is, to speak technically, capitate. The heads or buds are 

 first seen as slight swellings of the pedicle, with perhaps one or two 

 tentacles (Fig. 3a.) Sometimes they continue enlarging, and ultimately 

 arrive at the normal stage, (Fig, 3^,) but are often again withdrawn, 

 leaving uo indication of their previous existence, 



