and on a new Sjjecies o/" Protococcus. 423 



plant. The large groups, the baby groups, and the said spo- 

 rangia all abounded in the gum-bottle at the end of Sptember. 



SuvDuary of Observations. 



We will divide the development into four stages, viz. : — 

 1st, the development of the groups oi Sorastrum from the spo- 

 i-angium ; 2nd, the growth of these groups ; 3rd, the produc- 

 tion of the baby groups and consequent evacuation of the go- 

 nimic contents of some of the individuals of the parent group, 

 together with the retention of these contents by others, accom- 

 panied by change in figure of the body (inflation) and atrophy 

 of their spines ; and, 4th, the formation of the sporangium. 



1. On the 18th July, a spherical transparent cell, 18-6000ths 

 inch in diameter, was observed in a drop of the sedimentary 

 contents of the gum-bottle mentioned, which contents had 

 been placed under a microscope for examination. This cell 

 contained fifteen spherical groups of the compound Protococcus 

 called Sorastrum sjnnulosum^ Niig., each group consisting of 

 eight individuals and one large individual by itself, thus di- 

 viding the contents of the sporangial cell into sixteen portions. 

 Each of the groups was 5-6000ths inch in diameter, and each 

 individual composing them about 2-6000ths inch broad, while 

 the single individual was 4-6000ths inch broad (PL XI Y. 

 fig. 4) . The centre of the sporangial cell Avas occupied by 

 another spherical cell (e) 3-6000ths inch in diameter, which, 

 again, Avas apparently filled with small cells around one a 

 little larger, which was in the very centre of all ; while 

 from the spherical towards the confines of the sporangial cell 

 were seen the remains of the radiating branched septa (/"), 

 which originally divided the contents of the sporangium into 

 sixteen compartments. 



2. On the 14th August folloAving, a great number of free 

 grou])s (that is, Avithout cell-envelopes) AA'ere seen, averaging 

 8-60()0ths inch in diam., ex;clusive of the spines, and composed 

 respectively of eight, sixteen, and thirty-tAvo individuals, of 

 AAdiich each individual averaged 4-6000ths inch broad (fig. 1). 

 The largest groups measured lG-6000ths inch in diameter, 

 and the largest individuals o-GOOOths inch broad (figs. 2 & 3). 



3. On the 10th of September, baby groups began to appear 

 in connexion with the large groups ; and one of tliesc groups, 

 where there Avere two baby groups })rcsent, Avas transferred for 

 further observation to a cell depression in a slide covered with 

 a thin bit of glass, as before stated, for protection and to pre- 

 vent evaporation. Plere, in the course of twch-e hours after- 

 wards, three more baby groups Avere produced, making in all 

 five, of Avhich four A\'cre composed of sixteen individuals each. 



