The fresh cucumbers are filled with water in their tissues. When they are placed in a saltwater solution, osmosis occurs. A hypertonic solution means that there is a greater concentration of solutes (salt) in the surrounding liquid than their is the in the object(s) in the liquid (in this case the cucumbers). That means that the concentration of water is greater within the cucumbers than in the surrounding saltwater solution. During osmosis, water always flows through a semi-permeable membrane from an area of high concentration to an area of low concentration in an effort to equalize the concentrations. This means that water will flow out of the cucumbers and into the saltwater solution. As a result, the cucumbers will grow smaller in size as they lose water to become pickles. Since the cucumbers were tightly packed to begin with, they will become more loosely packed as they grow smaller.